Jupiter gives us Pluto in 2020

Mosaic image of Pluto and its largest moon Charon, captured around the time the New Horizons spacecraft swept closest to them on July 14, 2015. Image via NASA/ JHUAPL/ SwRI.

The year 2020 is exceptional for Jupiter and Pluto. These two worlds are having a triple conjunction this year. They’ll come together, move apart, and come together again three times in 2020. The first conjunction took place on April 5. The second one will come on June 30, and the final one on November 12. Because all of these Jupiter-Pluto conjunctions happen when these two planets are in our night sky (as opposed to being lost in the sun’s glare), this year’s Jupiter-Pluto alignment might be the best for centuries to come.

This year, very bright Jupiter and very faint Pluto will remain near each other throughout the year, closely aligned in front of the constellation Sagittarius. Pluto requires a telescope to be seen. No telescope? Try NASA’s Night Sky Network to find star parties and/or astronomy clubs near you.

And you don’t need a telescope to use your imagination. Throughout 2020, dazzling Jupiter will enable us to envision Pluto with the mind’s eye on the sky’s dome. First find Jupiter and – presto – you’ve nearly stumbled upon Pluto. Just remember, Jupiter outshines Pluto by several million times.

Where are these worlds now? Both rise into the southeast sky around nightfall or early evening in late June/early July 2020. Jupiter and Pluto climb upward throughout the evening hours, to reach the meridian roughly an hour after midnight, and then sit low in the southwest sky at daybreak.

Jupiter and Pluto are in conjunction on June 30, 2020. Less than one week later, in early July 2020, the moon strolls by the king planet Jupiter, the dwarf planet Pluto, and the ringed planet Saturn. Pluto, although not shown on the above chart, is just a touch south of Jupiter on the sky’s dome. All these planets swing to opposition in July 2020: Jupiter (July 14), Pluto (July 15), Saturn (July 20). Read more.

Of course, although Jupiter and Pluto nearly align along the same line of sight throughout 2020, these two worlds aren’t close together in space. Jupiter is a bit more than 5 astronomical units (AU) from the sun, while Pluto lodges way beyond Jupiter, in the Kuiper Belt, at about 34 AU from the sun. One astronomical unit (AU) = one sun/Earth distance.

Jupiter’s and Pluto’s present distance in AU via Heavens-Above

Here’s some observational data about Pluto for 2020, from In-the-Sky.org

Steven Bellavia in Mattituck, New York, captured Pluto on 2 separate nights, June 24 and June 27, 2019. In this animated gif, you can see that Pluto moved in front of the stars between those 2 nights. Steven wrote: “Most of the motion you see is actually from the Earth, not Pluto, since our motion changes our perspective of the much-closer Pluto against the backdrop of the much-farther stars.” Thanks, Steven!

Two planets are said to be in conjunction whenever they reside north and south of one another on the sky’s dome. Conjunctions of Jupiter and Pluto recur in periods of 12 to 13 years. The previous Jupiter-Pluto conjunction happened on December 11, 2007, and the one before that on December 2, 1994. After 2020, the next Jupiter-Pluto conjunction will occur on February 4, 2033, and the one following that on April 12, 2045. But the gap between Jupiter and Pluto at each one of these conjunctions is quite far apart, and the conjunctions of 1994, 2007, and 2033 happen so close to the sun that even Jupiter is lost in the sun’s glare.

Far and away, 2020 presents the best alignment of Jupiter and Pluto in the 21st century (2001 to 2100). What’s more, Jupiter and Pluto stage three conjunctions this year, as Jupiter passes less than one degree north of Pluto at each conjunction on April 5, June 30 and November 12, 2020. (For reference, the moon’s angular diameter spans about 1/2 degree of sky.) All of these conjunctions in 2020 take place in front of the constellation Sagittarius, with Jupiter first passing Pluto on April 5 in prograde (going eastward in front of the backdrop stars), then sweeping past Pluto on June 30 in retrograde (going westward relative to the background stars), and then for the final Jupiter-Pluto conjunction on November 12 in prograde (eastward).

All three Jupiter-Saturn conjunctions on April 5, June 30 and November 12, 2020 take pace place in front of the constellation Sagittarius, not far from the 5th-magnitude star 56 Sagittarii. Constellation chart via International Astronomical Union (IAU).

Most of the time, a Jupiter-Pluto conjunction in any year is a solitary event, as Jupiter laps Pluto going eastward, and never looks back. Triple conjunctions of Jupiter and Pluto – which occur over a period of about 7.4 months – are rare because Jupiter has to first catch Pluto going prograde (eastward), then in retrograde (westward) and then in prograde (eastward) again. The three-peat performance last happened in 1955-56 (November 2, 1955; February 8 and June 16, 1956), and will next occur in 2106-07 (July 13 and November 2, 2106; February 19, 2107). Yet, all three conjunctions in 1955-56 were widely spaced, and all three conjunctions in 2106-07 will be widely spaced, too.

Illustration showing why a superior planet appears to go in retrograde (westward in front of the backdrop stars of the zodiac). As seen from the north side of the solar system, all the planets orbit counterclockwise. When the faster-moving Earth goes by a slower-moving superior planet, that planet appears to go backward (in retrograde). In 2020, Mars is in retrograde from September 9 to November 15, Jupiter from May 14 to September 13, and Saturn from May 11 to September 29. Image via Wikimedia Commons.

In other words, as we said above, 2020 may well showcase the best Jupiter-Pluto alignment for centuries to come. Most excitingly, both Jupiter and Pluto will reach opposition in mid-July 2020. At opposition, a superior planet – any planet revolving around the sun outside of Earth’s orbit – resides opposite the sun in Earth’s sky.

Opposition happens when Earth flies between a superior planet, like Mars, and the sun. This happens yearly for most of the outer planets (and every other year for Mars). Illustration via Heavens-Above.

At opposition, a superior planet (or superior dwarf planet) rises at sunset and sets at sunrise, and is out all night long. It’s at opposition that a planet shines at its brightest best in Earth’s sky, and it’s at or near opposition that a planet comes closest to Earth for the year.

Jupiter reaches opposition on July 14, 2020, at about 08:00 UTC, and comes closest to Earth on July 15, 2020, at about 10:00 UTC.

Pluto reaches opposition on July 15, 2020, at about 19:00 UTC, and comes closest to Earth on July 13, 2020, at about 09:00 UTC.

In an uncanny bit of timing, the oppositions of Jupiter and Pluto happen almost concurrently in mid-July 2020. A planet reaches opposition midway through a retrograde. However, since Pluto resides so much farther from the sun than Jupiter does, Pluto’s retrograde lasts nearly 1 1/2 months (six weeks) longer than Jupiter’s four-month retrograde. So for near-unison oppositions, Pluto’s retrograde has to start – and end – approximately three weeks before – and after – Jupiter’s retrograde.

Jupiter and Pluto retrograde/opposition in 2020

Jupiter begins retrograde: May 14, 2020, in front of the constellation Sagittarius
Jupiter at opposition: July 14, 2020, in front of the constellation Sagittarius
Jupiter ends retrograde: September 13, 2020, in front of the constellation Sagittarius

Pluto begins retrograde: April 25, 2020, in front of the constellation Sagittarius
Pluto at opposition: July 15, 2020, in front of the constellation Sagittarius
Pluto ends retrograde: October 4, 2020, in front of the constellation Sagittarius

Jupiter-Pluto conjunction tables via Richard Nolle

Call it serendipity or synergy – or whatever – but the spectacular alignment of the king planet Jupiter with the dwarf planet Pluto doesn’t get much better than in 2020. A similarly good Jupiter-Pluto rendezvous might not happen again for a number of centuries to come.

Pluto as seen with a 12″ S/C telescope (14.3 mag.) on July 10, 2015. Photo by Efrain Morales of Sociedad de Astronomia del Caribe. More information about Pluto’s current location.

Bottom line: Jupiter is as easy to find as the dwarf planet Pluto is difficult. Jupiter is bright! It ranks as the fourth-brightest celestial object to light up the heavens, after the sun, moon and Venus. Pluto, on the other hand, is 1,600 times dimmer than the faintest star visible to the unaided eye. But Jupiter can help you find – or at least envision – Pluto this year. That’s because these two worlds are having a triple conjunction this year; they’re near each other on the sky’s dome all year and will come exceptionally close 3 times in 2020.

from EarthSky https://ift.tt/2XkisVG

Mosaic image of Pluto and its largest moon Charon, captured around the time the New Horizons spacecraft swept closest to them on July 14, 2015. Image via NASA/ JHUAPL/ SwRI.

The year 2020 is exceptional for Jupiter and Pluto. These two worlds are having a triple conjunction this year. They’ll come together, move apart, and come together again three times in 2020. The first conjunction took place on April 5. The second one will come on June 30, and the final one on November 12. Because all of these Jupiter-Pluto conjunctions happen when these two planets are in our night sky (as opposed to being lost in the sun’s glare), this year’s Jupiter-Pluto alignment might be the best for centuries to come.

This year, very bright Jupiter and very faint Pluto will remain near each other throughout the year, closely aligned in front of the constellation Sagittarius. Pluto requires a telescope to be seen. No telescope? Try NASA’s Night Sky Network to find star parties and/or astronomy clubs near you.

And you don’t need a telescope to use your imagination. Throughout 2020, dazzling Jupiter will enable us to envision Pluto with the mind’s eye on the sky’s dome. First find Jupiter and – presto – you’ve nearly stumbled upon Pluto. Just remember, Jupiter outshines Pluto by several million times.

Where are these worlds now? Both rise into the southeast sky around nightfall or early evening in late June/early July 2020. Jupiter and Pluto climb upward throughout the evening hours, to reach the meridian roughly an hour after midnight, and then sit low in the southwest sky at daybreak.

Jupiter and Pluto are in conjunction on June 30, 2020. Less than one week later, in early July 2020, the moon strolls by the king planet Jupiter, the dwarf planet Pluto, and the ringed planet Saturn. Pluto, although not shown on the above chart, is just a touch south of Jupiter on the sky’s dome. All these planets swing to opposition in July 2020: Jupiter (July 14), Pluto (July 15), Saturn (July 20). Read more.

Of course, although Jupiter and Pluto nearly align along the same line of sight throughout 2020, these two worlds aren’t close together in space. Jupiter is a bit more than 5 astronomical units (AU) from the sun, while Pluto lodges way beyond Jupiter, in the Kuiper Belt, at about 34 AU from the sun. One astronomical unit (AU) = one sun/Earth distance.

Jupiter’s and Pluto’s present distance in AU via Heavens-Above

Here’s some observational data about Pluto for 2020, from In-the-Sky.org

Steven Bellavia in Mattituck, New York, captured Pluto on 2 separate nights, June 24 and June 27, 2019. In this animated gif, you can see that Pluto moved in front of the stars between those 2 nights. Steven wrote: “Most of the motion you see is actually from the Earth, not Pluto, since our motion changes our perspective of the much-closer Pluto against the backdrop of the much-farther stars.” Thanks, Steven!

Two planets are said to be in conjunction whenever they reside north and south of one another on the sky’s dome. Conjunctions of Jupiter and Pluto recur in periods of 12 to 13 years. The previous Jupiter-Pluto conjunction happened on December 11, 2007, and the one before that on December 2, 1994. After 2020, the next Jupiter-Pluto conjunction will occur on February 4, 2033, and the one following that on April 12, 2045. But the gap between Jupiter and Pluto at each one of these conjunctions is quite far apart, and the conjunctions of 1994, 2007, and 2033 happen so close to the sun that even Jupiter is lost in the sun’s glare.

Far and away, 2020 presents the best alignment of Jupiter and Pluto in the 21st century (2001 to 2100). What’s more, Jupiter and Pluto stage three conjunctions this year, as Jupiter passes less than one degree north of Pluto at each conjunction on April 5, June 30 and November 12, 2020. (For reference, the moon’s angular diameter spans about 1/2 degree of sky.) All of these conjunctions in 2020 take place in front of the constellation Sagittarius, with Jupiter first passing Pluto on April 5 in prograde (going eastward in front of the backdrop stars), then sweeping past Pluto on June 30 in retrograde (going westward relative to the background stars), and then for the final Jupiter-Pluto conjunction on November 12 in prograde (eastward).

All three Jupiter-Saturn conjunctions on April 5, June 30 and November 12, 2020 take pace place in front of the constellation Sagittarius, not far from the 5th-magnitude star 56 Sagittarii. Constellation chart via International Astronomical Union (IAU).

Most of the time, a Jupiter-Pluto conjunction in any year is a solitary event, as Jupiter laps Pluto going eastward, and never looks back. Triple conjunctions of Jupiter and Pluto – which occur over a period of about 7.4 months – are rare because Jupiter has to first catch Pluto going prograde (eastward), then in retrograde (westward) and then in prograde (eastward) again. The three-peat performance last happened in 1955-56 (November 2, 1955; February 8 and June 16, 1956), and will next occur in 2106-07 (July 13 and November 2, 2106; February 19, 2107). Yet, all three conjunctions in 1955-56 were widely spaced, and all three conjunctions in 2106-07 will be widely spaced, too.

Illustration showing why a superior planet appears to go in retrograde (westward in front of the backdrop stars of the zodiac). As seen from the north side of the solar system, all the planets orbit counterclockwise. When the faster-moving Earth goes by a slower-moving superior planet, that planet appears to go backward (in retrograde). In 2020, Mars is in retrograde from September 9 to November 15, Jupiter from May 14 to September 13, and Saturn from May 11 to September 29. Image via Wikimedia Commons.

In other words, as we said above, 2020 may well showcase the best Jupiter-Pluto alignment for centuries to come. Most excitingly, both Jupiter and Pluto will reach opposition in mid-July 2020. At opposition, a superior planet – any planet revolving around the sun outside of Earth’s orbit – resides opposite the sun in Earth’s sky.

Opposition happens when Earth flies between a superior planet, like Mars, and the sun. This happens yearly for most of the outer planets (and every other year for Mars). Illustration via Heavens-Above.

At opposition, a superior planet (or superior dwarf planet) rises at sunset and sets at sunrise, and is out all night long. It’s at opposition that a planet shines at its brightest best in Earth’s sky, and it’s at or near opposition that a planet comes closest to Earth for the year.

Jupiter reaches opposition on July 14, 2020, at about 08:00 UTC, and comes closest to Earth on July 15, 2020, at about 10:00 UTC.

Pluto reaches opposition on July 15, 2020, at about 19:00 UTC, and comes closest to Earth on July 13, 2020, at about 09:00 UTC.

In an uncanny bit of timing, the oppositions of Jupiter and Pluto happen almost concurrently in mid-July 2020. A planet reaches opposition midway through a retrograde. However, since Pluto resides so much farther from the sun than Jupiter does, Pluto’s retrograde lasts nearly 1 1/2 months (six weeks) longer than Jupiter’s four-month retrograde. So for near-unison oppositions, Pluto’s retrograde has to start – and end – approximately three weeks before – and after – Jupiter’s retrograde.

Jupiter and Pluto retrograde/opposition in 2020

Jupiter begins retrograde: May 14, 2020, in front of the constellation Sagittarius
Jupiter at opposition: July 14, 2020, in front of the constellation Sagittarius
Jupiter ends retrograde: September 13, 2020, in front of the constellation Sagittarius

Pluto begins retrograde: April 25, 2020, in front of the constellation Sagittarius
Pluto at opposition: July 15, 2020, in front of the constellation Sagittarius
Pluto ends retrograde: October 4, 2020, in front of the constellation Sagittarius

Jupiter-Pluto conjunction tables via Richard Nolle

Call it serendipity or synergy – or whatever – but the spectacular alignment of the king planet Jupiter with the dwarf planet Pluto doesn’t get much better than in 2020. A similarly good Jupiter-Pluto rendezvous might not happen again for a number of centuries to come.

Pluto as seen with a 12″ S/C telescope (14.3 mag.) on July 10, 2015. Photo by Efrain Morales of Sociedad de Astronomia del Caribe. More information about Pluto’s current location.

Bottom line: Jupiter is as easy to find as the dwarf planet Pluto is difficult. Jupiter is bright! It ranks as the fourth-brightest celestial object to light up the heavens, after the sun, moon and Venus. Pluto, on the other hand, is 1,600 times dimmer than the faintest star visible to the unaided eye. But Jupiter can help you find – or at least envision – Pluto this year. That’s because these two worlds are having a triple conjunction this year; they’re near each other on the sky’s dome all year and will come exceptionally close 3 times in 2020.

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July 2020 guide to the bright planets

Click the name of a planet to learn more about its visibility in July 2020: Jupiter, Saturn, Mars, Venus, Mercury

Try Stellarium for a precise view of the planets from your location.

Want precise planet rise and set times? Click here for recommended almanacs

Watch for the moon to appear in the vicinity of Jupiter and Saturn for several days, centered on or near June 5, 2020. Read more.

Get up early on July 11 and 12, 2020, to see the waning moon with the red planet Mars. Read more.

Starting in mid-July 2020, use the waning crescent moon and Venus to locate Mercury near the horizon as the morning darkness begins to give way to dawn. Read more.

The waning crescent moon passes to the north of dazzling Venus on or near July 17. Read more.

Jupiter and Saturn are near one another on the sky’s dome, with Saturn following Jupiter westward across the sky from early evening until dawn. Around the world, Jupiter and nearby Saturn rise during nightfall in early July, around sunset in mid-July, and before sundown by the month’s end.

It’s a banner month for these gas giant worlds, as Jupiter and Saturn both come to opposition this month. At and around opposition, Earth swings closest to Jupiter and Saturn for the year, and Jupiter and Saturn, in turn, shine at their brightest best and are out all night long.

Read more: Jupiter at opposition on July 13-14

Read more: We go between Saturn and the sun July 20

Look first for brilliant Jupiter and you’ll find Saturn a rather short hop to the east of the king planet. Although Saturn is easily as bright as a 1st-magnitude star, the ringed planet pales next the the king planet Jupiter, which outshines Saturn by some 15 times. After all, Jupiter ranks as the fourth brightest celestial object, after the sun, moon, and the planet Venus, respectively.

Watch for the moon in the vicinity of Jupiter and Saturn for several days, centered on or near July 5.

In July 2020, Jupiter and Saturn climb up highest for the night around midnight. Given an unobstructed southeast horizon, you should have little trouble catching the planets Jupiter and Saturn low in the southeast sky at nightfall or early evening. Use Jupiter and Saturn to find the “Teapot” asterism in the constellation Sagittarius the Archer. Read more.

Mars is the first of the three bright morning planets to rise in July 2020: Mars comes up at late night, roughly around midnight. Then, a few to several hours later, Venus rises into the predawn sky; and by the second half of July 2020, Mercury will appear below Venus at morning dawn.

Sometime this month, Mars will rise before midnight, to sit low in the east at late evening. By August, look for Mars to be up by mid-to-late evening.

At mid-northern latitudes, Mars rises around the midnight hour in early July, and roughly 10 p.m. (11 p.m. daylight-saving time) by the month’s end. By midnight, we mean midway between sunset and sunrise.

At temperate latitudes in the Southern Hemisphere, Mars comes up at or near the midnight hour in early July, and about an hour earlier by the month’s end.

Let the waning moon help guide your eye to Mars on the mornings of July 11 and 12.

In July 2020 … you’ll find Mars respectably bright – easily as brilliant as a 1st-magnitude star – in the predawn/dawn sky. Earth will be rushing along in its smaller, faster orbit, gaining on Mars, the fourth planet outward from the sun. Throughout the next three months, watch for Mars to brighten dramatically as Earth closes in on Mars. The red planet will appear brightest in our sky and fiery red – around the time of its opposition – when Earth passes between Mars and the sun on October 13, 2020. At that wondrous time, Mars will actually supplant Jupiter as the sky’s fourth-brightest celestial body, after the sun, moon, and the planet Venus, respectively.

View at EarthSky Community Photos. | From Paul Armstrong, who took this photo of Mars, Saturn and Jupiter on the morning of April 15, 2020, from Exmoor, U.K. Jupiter is at the upper right, Mars at center left, with Saturn between them. In May 2020, Jupiter and Saturn were closer together, whereas Mars was farther away from Jupiter and Saturn. Thanks, Paul!

Venus – the brightest planet – rushed between the Earth and sun (inferior conjunction) on June 3, 2020. At that point, it transitioned out of the evening sky and into the morning sky. We first saw Venus reappear in the east at dawn around mid-June. Throughout July, this blazing world will climb progressively higher into the eastern predawn sky.

At mid-northern latitudes, Venus rises about 2 hours before the sun in early July, increasing to about 3 hours by the month’s end.

At and near the equator, Venus rises about 2 1/3 hours before the sun in early July, increasing to over 3 hours near the month’s end.

At temperate latitudes in the Southern Hemisphere, Venus rises about 2 2/3 hours before the sun in early July, increasing to over 3 hours by the month’s end.

Inferior conjunction – when Venus sweeps between the sun and Earth – happened on June 3, 2020. Just before inferior conjunction, we saw Venus as a thin waning crescent in the evening sky; and just after inferior conjunction, we saw Venus as a thin waxing crescent in the morning sky. In July 2020, Venus will start the month about 19 percent illuminated and end the month about 42 percent illuminated. Image via UCLA.

Throughout July, Venus in its faster orbit around the sun will be going farther and farther away from Earth. As viewed through the telescope, Venus’ waxing crescent phase will widen, yet its overall disk size will shrink. Venus’ disk is 19 percent illuminated in early July, and about 42 percent illuminated by the month’s end; Venus’ angular diameter, on the other hand, will shrink to 2/3rd the size by the month’s end.

Look for Venus to beam at its brightest in the morning sky on or around July 10, 2020, when Venus displays its greatest illuminated extent on the sky’s dome. Venus always beams at its brightest best when its disk is about one-quarter illuminated by sunshine. In fact, if you’re up before dawn, note that Venus at its brightest closely couples up with Aldebaran, the brightest star in the constellation Taurus the Bull.

If you’re up before dawn July 10, 2020, look for Aldebaran, the brightest star in the constellation Taurus the Bull, quite close to Venus on the sky’s dome. Read more.

Watch for the waning crescent moon in the vicinity of Venus for several days, centered on or near July 17.

Mercury transitions out of the evening sky and into the morning sky on July 1, and then reaches its greatest elongation in the morning sky on July 22, 2020. We expect Mercury to become visible in the eastern dawn sky around mid-month. Have binoculars handy, however, for Mercury has to compete with the glow of morning twilight. Given an unobstructed horizon in the direction of sunrise, you have a reasonably good chance of catching Mercury in the second half of July, as this world brightens throughout the month.

For several mornings, starting on or around July 16, let the waning crescent moon and the brilliant planet Venus guide you to Mercury’s place near the horizon.

Mercury reaches its greatest elongation on July 22, 2020, at which juncture Mercury will be 20 degrees west of the sun. After that date, Mercury will slowly fall sunward day by day.

Here are Mercury’s approximate rising times for 40 degrees north latitude, the equator (0 degrees latitude) and 35 degrees south latitude (given an unobstructed eastern horizon):

40 degrees north latitude:
July 15: Mercury rises 66 minutes (1 1/10 hours) before the sun
July 22: Mercury rises 90 minutes (1 1/2 hours) before the sun
August 1: Mercury rises 80 minutes (1 1/3 hours) before the sun

Equator (0 degrees latitude)
July 15: Mercury rises 75 minutes (1 1/4 hours) before sunrise
July 22: Mercury rises 84 minutes (1 2/5 hours) before sunrise
August 1: Mercury rises 66 minutes (1 1/10 hours) before sunrise

35 degrees south latitude
July 15: Mercury rises 80 minutes (1 1/3 hours) before sunrise
July 22: Mercury rises 80 minutes (1 1/3 hours) before sunrise
August 1: Mercury rises 45 minutes (3/4 hour) before sunrise

For more specific information, check out recommended sky almanacs

What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.

Skywatcher, by Predrag Agatonovic.

Bottom line: July 2020 presents all 5 bright solar system planets. Catch Jupiter and Saturn at early evening and throughout the night, Mars between midnight and dawn, Venus in the predawn/dawn sky, and Mercury below Venus at dawn in the second half of July.

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Click the name of a planet to learn more about its visibility in July 2020: Jupiter, Saturn, Mars, Venus, Mercury

Try Stellarium for a precise view of the planets from your location.

Want precise planet rise and set times? Click here for recommended almanacs

Watch for the moon to appear in the vicinity of Jupiter and Saturn for several days, centered on or near June 5, 2020. Read more.

Get up early on July 11 and 12, 2020, to see the waning moon with the red planet Mars. Read more.

Starting in mid-July 2020, use the waning crescent moon and Venus to locate Mercury near the horizon as the morning darkness begins to give way to dawn. Read more.

The waning crescent moon passes to the north of dazzling Venus on or near July 17. Read more.

Jupiter and Saturn are near one another on the sky’s dome, with Saturn following Jupiter westward across the sky from early evening until dawn. Around the world, Jupiter and nearby Saturn rise during nightfall in early July, around sunset in mid-July, and before sundown by the month’s end.

It’s a banner month for these gas giant worlds, as Jupiter and Saturn both come to opposition this month. At and around opposition, Earth swings closest to Jupiter and Saturn for the year, and Jupiter and Saturn, in turn, shine at their brightest best and are out all night long.

Read more: Jupiter at opposition on July 13-14

Read more: We go between Saturn and the sun July 20

Look first for brilliant Jupiter and you’ll find Saturn a rather short hop to the east of the king planet. Although Saturn is easily as bright as a 1st-magnitude star, the ringed planet pales next the the king planet Jupiter, which outshines Saturn by some 15 times. After all, Jupiter ranks as the fourth brightest celestial object, after the sun, moon, and the planet Venus, respectively.

Watch for the moon in the vicinity of Jupiter and Saturn for several days, centered on or near July 5.

In July 2020, Jupiter and Saturn climb up highest for the night around midnight. Given an unobstructed southeast horizon, you should have little trouble catching the planets Jupiter and Saturn low in the southeast sky at nightfall or early evening. Use Jupiter and Saturn to find the “Teapot” asterism in the constellation Sagittarius the Archer. Read more.

Mars is the first of the three bright morning planets to rise in July 2020: Mars comes up at late night, roughly around midnight. Then, a few to several hours later, Venus rises into the predawn sky; and by the second half of July 2020, Mercury will appear below Venus at morning dawn.

Sometime this month, Mars will rise before midnight, to sit low in the east at late evening. By August, look for Mars to be up by mid-to-late evening.

At mid-northern latitudes, Mars rises around the midnight hour in early July, and roughly 10 p.m. (11 p.m. daylight-saving time) by the month’s end. By midnight, we mean midway between sunset and sunrise.

At temperate latitudes in the Southern Hemisphere, Mars comes up at or near the midnight hour in early July, and about an hour earlier by the month’s end.

Let the waning moon help guide your eye to Mars on the mornings of July 11 and 12.

In July 2020 … you’ll find Mars respectably bright – easily as brilliant as a 1st-magnitude star – in the predawn/dawn sky. Earth will be rushing along in its smaller, faster orbit, gaining on Mars, the fourth planet outward from the sun. Throughout the next three months, watch for Mars to brighten dramatically as Earth closes in on Mars. The red planet will appear brightest in our sky and fiery red – around the time of its opposition – when Earth passes between Mars and the sun on October 13, 2020. At that wondrous time, Mars will actually supplant Jupiter as the sky’s fourth-brightest celestial body, after the sun, moon, and the planet Venus, respectively.

View at EarthSky Community Photos. | From Paul Armstrong, who took this photo of Mars, Saturn and Jupiter on the morning of April 15, 2020, from Exmoor, U.K. Jupiter is at the upper right, Mars at center left, with Saturn between them. In May 2020, Jupiter and Saturn were closer together, whereas Mars was farther away from Jupiter and Saturn. Thanks, Paul!

Venus – the brightest planet – rushed between the Earth and sun (inferior conjunction) on June 3, 2020. At that point, it transitioned out of the evening sky and into the morning sky. We first saw Venus reappear in the east at dawn around mid-June. Throughout July, this blazing world will climb progressively higher into the eastern predawn sky.

At mid-northern latitudes, Venus rises about 2 hours before the sun in early July, increasing to about 3 hours by the month’s end.

At and near the equator, Venus rises about 2 1/3 hours before the sun in early July, increasing to over 3 hours near the month’s end.

At temperate latitudes in the Southern Hemisphere, Venus rises about 2 2/3 hours before the sun in early July, increasing to over 3 hours by the month’s end.

Inferior conjunction – when Venus sweeps between the sun and Earth – happened on June 3, 2020. Just before inferior conjunction, we saw Venus as a thin waning crescent in the evening sky; and just after inferior conjunction, we saw Venus as a thin waxing crescent in the morning sky. In July 2020, Venus will start the month about 19 percent illuminated and end the month about 42 percent illuminated. Image via UCLA.

Throughout July, Venus in its faster orbit around the sun will be going farther and farther away from Earth. As viewed through the telescope, Venus’ waxing crescent phase will widen, yet its overall disk size will shrink. Venus’ disk is 19 percent illuminated in early July, and about 42 percent illuminated by the month’s end; Venus’ angular diameter, on the other hand, will shrink to 2/3rd the size by the month’s end.

Look for Venus to beam at its brightest in the morning sky on or around July 10, 2020, when Venus displays its greatest illuminated extent on the sky’s dome. Venus always beams at its brightest best when its disk is about one-quarter illuminated by sunshine. In fact, if you’re up before dawn, note that Venus at its brightest closely couples up with Aldebaran, the brightest star in the constellation Taurus the Bull.

If you’re up before dawn July 10, 2020, look for Aldebaran, the brightest star in the constellation Taurus the Bull, quite close to Venus on the sky’s dome. Read more.

Watch for the waning crescent moon in the vicinity of Venus for several days, centered on or near July 17.

Mercury transitions out of the evening sky and into the morning sky on July 1, and then reaches its greatest elongation in the morning sky on July 22, 2020. We expect Mercury to become visible in the eastern dawn sky around mid-month. Have binoculars handy, however, for Mercury has to compete with the glow of morning twilight. Given an unobstructed horizon in the direction of sunrise, you have a reasonably good chance of catching Mercury in the second half of July, as this world brightens throughout the month.

For several mornings, starting on or around July 16, let the waning crescent moon and the brilliant planet Venus guide you to Mercury’s place near the horizon.

Mercury reaches its greatest elongation on July 22, 2020, at which juncture Mercury will be 20 degrees west of the sun. After that date, Mercury will slowly fall sunward day by day.

Here are Mercury’s approximate rising times for 40 degrees north latitude, the equator (0 degrees latitude) and 35 degrees south latitude (given an unobstructed eastern horizon):

40 degrees north latitude:
July 15: Mercury rises 66 minutes (1 1/10 hours) before the sun
July 22: Mercury rises 90 minutes (1 1/2 hours) before the sun
August 1: Mercury rises 80 minutes (1 1/3 hours) before the sun

Equator (0 degrees latitude)
July 15: Mercury rises 75 minutes (1 1/4 hours) before sunrise
July 22: Mercury rises 84 minutes (1 2/5 hours) before sunrise
August 1: Mercury rises 66 minutes (1 1/10 hours) before sunrise

35 degrees south latitude
July 15: Mercury rises 80 minutes (1 1/3 hours) before sunrise
July 22: Mercury rises 80 minutes (1 1/3 hours) before sunrise
August 1: Mercury rises 45 minutes (3/4 hour) before sunrise

For more specific information, check out recommended sky almanacs

What do we mean by bright planet? By bright planet, we mean any solar system planet that is easily visible without an optical aid and that has been watched by our ancestors since time immemorial. In their outward order from the sun, the five bright planets are Mercury, Venus, Mars, Jupiter and Saturn. These planets actually do appear bright in our sky. They are typically as bright as – or brighter than – the brightest stars. Plus, these relatively nearby worlds tend to shine with a steadier light than the distant, twinkling stars. You can spot them, and come to know them as faithful friends, if you try.

Skywatcher, by Predrag Agatonovic.

Bottom line: July 2020 presents all 5 bright solar system planets. Catch Jupiter and Saturn at early evening and throughout the night, Mars between midnight and dawn, Venus in the predawn/dawn sky, and Mercury below Venus at dawn in the second half of July.

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Circumpolar stars don’t rise or set

Circumpolar stars stay above the horizon all hours of the day, every day of the year. These stars neither rise nor set but always remain in our sky. Even when you can’t see them – when the sun is out and it’s daytime – these stars are up there, circling endlessly around the sky’s north or south pole.

For instance, the stars of the famous Big Dipper asterism are circumpolar at all latitudes north of 41 degrees north latitude, which includes the northern half of the mainland United States and most of Europe.

From the northern U.S., Canada or similar latitudes, the Big Dipper is circumpolar, always above your horizon. Image shows Big Dipper at midnight at various seasons. “Spring up and fall down” for the Dipper’s appearance in our northern sky. It ascends in the northeast on spring evenings and descends in the northwest on fall evenings. Image via Night Sky Interlude – Spring Skies.

How many circumpolar stars appear in your sky depends on where you are. At the Earth’s North and South Poles, every visible star is circumpolar. That is, at Earth’s North Pole, every star north of the celestial equator is circumpolar, while every star south of the celestial equator stays below the horizon. At the Earth’s South Pole, it’s the exact opposite. Every star south of the celestial equator is circumpolar, whereas every star north of the celestial equator remains beneath the horizon.

At the Earth’s equator, no star is circumpolar because all the stars rise and set daily in that part of the world. You can (theoretically) see every star in the night sky over the course of one year. In practice, of course, things like clouds and horizon haze get in the way.

Places between the equator and poles have some stars that are circumpolar, some stars that rise and set daily (like the sun), and some stars that remain below the horizon all year round. In short, the closer you are to the North or South Pole, the greater the circle of circumpolar stars; the closer you are to the Earth’s equator, the smaller the circle of circumpolar stars.

We in the Northern Hemisphere are lucky to have a moderately-bright star, Polaris, nearly coinciding with the north celestial pole – the point in the sky that’s at zenith (straight overhead) at the Earth’s North Pole.

Draw an imaginary line straight down from Polaris, the North Star, to the horizon, and presto, you have what it takes to draw out the circle of circumpolar stars in your sky.

In the Northern Hemisphere, an imaginary vertical line from the north celestial pole to your horizon serves as a radius measure for the circle of circumpolar stars in your sky. The closer you are to the Earth’s North Pole, the closer the north celestial pole is to your zenith (overhead point).

For people in the Northern Hemisphere, Polaris nearly pinpoints the center of the great big circle of circumpolar stars on the sky’s dome; and the imaginary vertical line from Polaris to the horizon depicts the radius measure. (See the above chart, which has this line drawn in for you.) Let your arm serve as a circle compass, enabling you to envision the circle of circumpolar stars with your mind’s eye. Closer to the equator, the circle of circumpolar stars grows smaller; nearer to the North Pole (or South Pole) the circle of circumpolar stars grows larger.

This technique for locating the circle of circumpolar stars works in the Southern Hemisphere, as well. However, it’s trickier to star-hop to the south celestial pole: the point on the sky’s dome that’s at zenith over the Earth’s South Pole. Practiced stargazers in the Southern Hemisphere rely on the Southern Cross, and key stars, to star-hop to the south celestial pole, as depicted in the illustration below:

Star-hopping to south celestial pole via the Southern Cross and the bright stars Alpha Centauri and Hadar. Read more: Use the Southern Cross to find due south.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Big Dipper is circumpolar at 41 degrees north latitude, and all latitudes farther north.

The Southern Cross is circumpolar anywhere south of 35 degrees south latitude; yet, in the Northern Hemisphere, it’s the W or M-shaped constellation Cassiopeia that’s circumpolar at all places north of 35 degrees north latitude. (Scroll upward to the chart showing Cassiopeia at nightfall for mid-northern latitudes.)

By the way, Cassiopeia lies on the opposite side of Polaris from the Big Dipper. So from mid-northern latitudes, the Big Dipper and Polaris help you to locate Cassiopeia. See the above animation, in which all the stars revolve full circle around the celestial pole each day – or more precisely: every 23 hours and 56 minutes.

If Cassiopeia is circumpolar in your sky, then the Southern Cross never climbs above your horizon; and conversely, if the Southern Cross is circumpolar in your sky, then the constellation Cassiopeia never climbs above the horizon.

As seen from the tropics (and subtropics), neither the Southern Cross nor Cassiopeia is circumpolar. From this part of the world, the Southern Cross rises over the southern horizon when Cassiopeia sinks below the northern horizon; and conversely, Cassiopeia rises over the northern horizon when the Southern Cross sinks below the southern horizon.

Sky wheeling around Polaris, the North Star. Image via Shutterstock.

Bottom line: Circumpolar stars stay above the horizon all hours of the day, every day of the year. Although you can’t see them, they’re up even in daytime.

Read more: Use the Southern Cross to find due south

.

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Circumpolar stars stay above the horizon all hours of the day, every day of the year. These stars neither rise nor set but always remain in our sky. Even when you can’t see them – when the sun is out and it’s daytime – these stars are up there, circling endlessly around the sky’s north or south pole.

For instance, the stars of the famous Big Dipper asterism are circumpolar at all latitudes north of 41 degrees north latitude, which includes the northern half of the mainland United States and most of Europe.

From the northern U.S., Canada or similar latitudes, the Big Dipper is circumpolar, always above your horizon. Image shows Big Dipper at midnight at various seasons. “Spring up and fall down” for the Dipper’s appearance in our northern sky. It ascends in the northeast on spring evenings and descends in the northwest on fall evenings. Image via Night Sky Interlude – Spring Skies.

How many circumpolar stars appear in your sky depends on where you are. At the Earth’s North and South Poles, every visible star is circumpolar. That is, at Earth’s North Pole, every star north of the celestial equator is circumpolar, while every star south of the celestial equator stays below the horizon. At the Earth’s South Pole, it’s the exact opposite. Every star south of the celestial equator is circumpolar, whereas every star north of the celestial equator remains beneath the horizon.

At the Earth’s equator, no star is circumpolar because all the stars rise and set daily in that part of the world. You can (theoretically) see every star in the night sky over the course of one year. In practice, of course, things like clouds and horizon haze get in the way.

Places between the equator and poles have some stars that are circumpolar, some stars that rise and set daily (like the sun), and some stars that remain below the horizon all year round. In short, the closer you are to the North or South Pole, the greater the circle of circumpolar stars; the closer you are to the Earth’s equator, the smaller the circle of circumpolar stars.

We in the Northern Hemisphere are lucky to have a moderately-bright star, Polaris, nearly coinciding with the north celestial pole – the point in the sky that’s at zenith (straight overhead) at the Earth’s North Pole.

Draw an imaginary line straight down from Polaris, the North Star, to the horizon, and presto, you have what it takes to draw out the circle of circumpolar stars in your sky.

In the Northern Hemisphere, an imaginary vertical line from the north celestial pole to your horizon serves as a radius measure for the circle of circumpolar stars in your sky. The closer you are to the Earth’s North Pole, the closer the north celestial pole is to your zenith (overhead point).

For people in the Northern Hemisphere, Polaris nearly pinpoints the center of the great big circle of circumpolar stars on the sky’s dome; and the imaginary vertical line from Polaris to the horizon depicts the radius measure. (See the above chart, which has this line drawn in for you.) Let your arm serve as a circle compass, enabling you to envision the circle of circumpolar stars with your mind’s eye. Closer to the equator, the circle of circumpolar stars grows smaller; nearer to the North Pole (or South Pole) the circle of circumpolar stars grows larger.

This technique for locating the circle of circumpolar stars works in the Southern Hemisphere, as well. However, it’s trickier to star-hop to the south celestial pole: the point on the sky’s dome that’s at zenith over the Earth’s South Pole. Practiced stargazers in the Southern Hemisphere rely on the Southern Cross, and key stars, to star-hop to the south celestial pole, as depicted in the illustration below:

Star-hopping to south celestial pole via the Southern Cross and the bright stars Alpha Centauri and Hadar. Read more: Use the Southern Cross to find due south.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Big Dipper is circumpolar at 41 degrees north latitude, and all latitudes farther north.

The Southern Cross is circumpolar anywhere south of 35 degrees south latitude; yet, in the Northern Hemisphere, it’s the W or M-shaped constellation Cassiopeia that’s circumpolar at all places north of 35 degrees north latitude. (Scroll upward to the chart showing Cassiopeia at nightfall for mid-northern latitudes.)

By the way, Cassiopeia lies on the opposite side of Polaris from the Big Dipper. So from mid-northern latitudes, the Big Dipper and Polaris help you to locate Cassiopeia. See the above animation, in which all the stars revolve full circle around the celestial pole each day – or more precisely: every 23 hours and 56 minutes.

If Cassiopeia is circumpolar in your sky, then the Southern Cross never climbs above your horizon; and conversely, if the Southern Cross is circumpolar in your sky, then the constellation Cassiopeia never climbs above the horizon.

As seen from the tropics (and subtropics), neither the Southern Cross nor Cassiopeia is circumpolar. From this part of the world, the Southern Cross rises over the southern horizon when Cassiopeia sinks below the northern horizon; and conversely, Cassiopeia rises over the northern horizon when the Southern Cross sinks below the southern horizon.

Sky wheeling around Polaris, the North Star. Image via Shutterstock.

Bottom line: Circumpolar stars stay above the horizon all hours of the day, every day of the year. Although you can’t see them, they’re up even in daytime.

Read more: Use the Southern Cross to find due south

.

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What’s a penumbral eclipse of the moon?

April 2013 penumbral eclipse by Stanislaus Ronny Terrance. See the dark shading on one edge of the moon?

Next penumbral lunar eclipse: July 4-5, 2020

An eclipse of the moon can only happen at full moon, when the sun, Earth and moon line up in space, with Earth in the middle. At such times, Earth’s shadow falls on the moon, creating a lunar eclipse. Lunar eclipses happen a minimum of two times to a maximum of five times a year. There are three kinds of lunar eclipses: total, partial and penumbral.

In a total eclipse of the moon, the inner part of Earth’s shadow, called the umbra, falls on the moon’s face. At mid-eclipse, the entire moon is in shadow, which may appear blood red.

In a partial lunar eclipse, the umbra takes a bite out of only a fraction of the moon. The dark bite grows larger, and then recedes, never reaching the total phase.

In a penumbral lunar eclipse, only the more diffuse outer shadow of Earth – the penumbra – falls on the moon’s face. This third kind of lunar eclipse is much more subtle, and much more difficult to observe, than either a total or partial eclipse of the moon. There is never a dark bite taken out of the moon, as in a partial eclipse. The eclipse never progresses to reach the dramatic minutes of totality. At best, at mid-eclipse, very observant people will notice a dark shading on the moon’s face. Others will look and notice nothing at all.

According to eclipse expert Fred Espenak, about 35% of all eclipses are penumbral. Another 30% are partial eclipses, where it appears as if a dark bite has been taken out of the moon. And the final 35% go all the way to becoming total eclipses of the moon, a beautiful natural event.

View larger. | Left, an ordinary full moon with no eclipse. Right, full moon in penumbral eclipse on November 20, 2002. Master eclipse photographer Fred Espenak took this photo when the moon was 88.9% immersed in Earth’s penumbral shadow. There’s no dark bite taken out of the moon. A penumbral eclipse creates only a dark shading on the moon’s face.

In a lunar eclipse, Earth’s shadow falls on the moon. If the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. If the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via Fred Espenak’s Lunar Eclipses for Beginners.

Here’s what a partial lunar eclipse looks like. Astronomer Alan Dyer caught it from his home in southern Alberta, Canada, in June 2012. It was pre-dawn, near moonset. Image copyright Alan Dyer. Used with permission.

This is what a total eclipse looks like. This is the total eclipse of October 27, 2004, via Fred Espenak of NASA, otherwise known as Mr. Eclipse. Visit Fred’s page here.

Bottom line: There are three kinds of lunar eclipses: total, partial and penumbral. A penumbral eclipse is very subtle. At no time does a dark bite appear to be taken out of the moon. Instead, at mid-eclipse, observant people will notice a shading on the moon’s face.

Next penumbral lunar eclipse: July 4-5, 2020

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April 2013 penumbral eclipse by Stanislaus Ronny Terrance. See the dark shading on one edge of the moon?

Next penumbral lunar eclipse: July 4-5, 2020

An eclipse of the moon can only happen at full moon, when the sun, Earth and moon line up in space, with Earth in the middle. At such times, Earth’s shadow falls on the moon, creating a lunar eclipse. Lunar eclipses happen a minimum of two times to a maximum of five times a year. There are three kinds of lunar eclipses: total, partial and penumbral.

In a total eclipse of the moon, the inner part of Earth’s shadow, called the umbra, falls on the moon’s face. At mid-eclipse, the entire moon is in shadow, which may appear blood red.

In a partial lunar eclipse, the umbra takes a bite out of only a fraction of the moon. The dark bite grows larger, and then recedes, never reaching the total phase.

In a penumbral lunar eclipse, only the more diffuse outer shadow of Earth – the penumbra – falls on the moon’s face. This third kind of lunar eclipse is much more subtle, and much more difficult to observe, than either a total or partial eclipse of the moon. There is never a dark bite taken out of the moon, as in a partial eclipse. The eclipse never progresses to reach the dramatic minutes of totality. At best, at mid-eclipse, very observant people will notice a dark shading on the moon’s face. Others will look and notice nothing at all.

According to eclipse expert Fred Espenak, about 35% of all eclipses are penumbral. Another 30% are partial eclipses, where it appears as if a dark bite has been taken out of the moon. And the final 35% go all the way to becoming total eclipses of the moon, a beautiful natural event.

View larger. | Left, an ordinary full moon with no eclipse. Right, full moon in penumbral eclipse on November 20, 2002. Master eclipse photographer Fred Espenak took this photo when the moon was 88.9% immersed in Earth’s penumbral shadow. There’s no dark bite taken out of the moon. A penumbral eclipse creates only a dark shading on the moon’s face.

In a lunar eclipse, Earth’s shadow falls on the moon. If the moon passes through the dark central shadow of Earth – the umbra – a partial or total lunar eclipse takes place. If the moon only passes through the outer part of the shadow (the penumbra), a subtle penumbral eclipse occurs. Diagram via Fred Espenak’s Lunar Eclipses for Beginners.

Here’s what a partial lunar eclipse looks like. Astronomer Alan Dyer caught it from his home in southern Alberta, Canada, in June 2012. It was pre-dawn, near moonset. Image copyright Alan Dyer. Used with permission.

This is what a total eclipse looks like. This is the total eclipse of October 27, 2004, via Fred Espenak of NASA, otherwise known as Mr. Eclipse. Visit Fred’s page here.

Bottom line: There are three kinds of lunar eclipses: total, partial and penumbral. A penumbral eclipse is very subtle. At no time does a dark bite appear to be taken out of the moon. Instead, at mid-eclipse, observant people will notice a shading on the moon’s face.

Next penumbral lunar eclipse: July 4-5, 2020

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10 great places to see meteor showers in the US

Meteors over Death Valley via Will Li/ AccuWeather.

AccuWeather originally published this article in June 2020. EarthSky editors also contributed.

Meteor showers can be a trickle, or they can be astounding natural events. Either way, these light shows give people a glimpse of the vastness of space and, in many ways, motivate people to be more in tune with nature. However, there’s one major hurdle that prevents many people from ever experiencing a meteor shower: light pollution from home and city outdoor lighting. Unless you live in a dark country location, your own backyard probably isn’t the best place to watch a meteor shower. With this in mind, here’s a list of 10 places to see the meteor showers in the U.S., recommended by AccuWeather.

Want to know when to watch? Try EarthSky’s meteor shower guide for 2020

Got a great stargazing location to recommend? Recommend here

Try EarthSky’s Best Places to Stargaze page for lots more recommended dark sites.

Note: In 2020, some public parks are closed due to Covid-19. Be sure to check with these parks first, before you go.

1. Big Bend National Park, Texas. The world’s best places to see meteor showers are going to be untouched environments, such as national parks. Big Bend National Park in far west Texas has night skies that are nothing short of magical. It’s a great place to watch a meteor shower!

View larger. | Sergio Garcia Rill caught the Perseid meteor shower in Big Bend National Park in 2015. He wrote, “Well, here’s the result of a night at the Cerro Castellan area inside Big Bend. This photo has got 23 meteors in it, as well as me trying to find some shooting stars with my flashlight.” Thank you Sergio!

2. Joshua Tree National Park, California. Given the many densely populated cities in California, it’s hard to imagine that this state would have good sites to see meteor showers. But – like all states in the United States – it does. Beloved Joshua Tree National Park is one of the places in California to see stars and meteors.

Joan Schipper wrote: “The Sierra Club Camera Committee went to Joshua Tree National Park trying to catch some Orionid meteors in pixels. Eight of us were staked out in various locations at White Tank campground. This is my 3rd attempt to capture meteors and my 2nd bit of success.”

3. Death Valley, California/Nevada. Don’t let its name scare you. Straddling California and Nevada, Death Valley – with its naturally dark skies – is another hot spot for meteor showers and stargazing.

The 2018 Geminid meteor shower rains down on Death Valley, as seen from Zabriskie Point. Comet Wirtanen is visible in the upper left, below and to the left of Pleiades. Image via Rick Whitacre.

4. Finger Lakes, New York. Much like California, New York has densely populated areas. But New York has the beauty of the Finger Lakes for people to enjoy. Because Finger Lakes are located away from the bright lights of the city, its night skies provide an incredible view.

5. The area around Tucson, Arizona. This desert region is surrounded by tall hills and mountains, places where you can get up high to look at the sky.

Draconids near Tucson, Arizona, in 2013, by our friend Sean Parker Photography.

6. Denali National Park, Alaska. Generally speaking, Alaska is a place many would expect to find on this list. The state is full of natural beauty. That said, Denali National Park in Alaska is known for its dark skies.

7. Brockway Mountain, Michigan. A great place for stargazing and meteor-watching in the upper midwest.

8. Big Pine Key, Florida. If Alaska is an obvious candidate for seeing meteor showers, Florida might be the opposite. Yet Big Pine Key in Florida has an annual winter party for stargazing.

If you’re in Florida for stargazing, be sure to check with Cape Canaveral to see if there are any space launches you can watch, to add to your experience. Richard Benzinger in Crescent Beach, Florida, caught the March 16, 2017, SpaceX launch of Echostar XXIII from Cape Canaveral, shooting southeast. Thanks, Richard!

9. White Sands, New Mexico. While it is not as flat as Death Valley, White Sands is flat enough and dark enough to provide a great platform for meteor-watching.

10. Canyonlands National Park, Utah. Stargazing and meteor-watching under Utah’s glorious night skies … what could be better?

View larger. | Quinn Pratt caught this 2014 photo of night skies over Canyonlands National Park. Thank you, Quinn!

Bottom line: Ten recommended sites for watching meteor showers, from AccuWeather and the editors of EarthSky.

Want to know when to watch meteor showers? Try EarthSky’s meteor shower guide for 2020

Got a great stargazing location to recommend? Recommend here

Try EarthSky’s Best Places to Stargaze page for lots more recommended dark sites.

from EarthSky https://ift.tt/3g3zPnw

Meteors over Death Valley via Will Li/ AccuWeather.

AccuWeather originally published this article in June 2020. EarthSky editors also contributed.

Meteor showers can be a trickle, or they can be astounding natural events. Either way, these light shows give people a glimpse of the vastness of space and, in many ways, motivate people to be more in tune with nature. However, there’s one major hurdle that prevents many people from ever experiencing a meteor shower: light pollution from home and city outdoor lighting. Unless you live in a dark country location, your own backyard probably isn’t the best place to watch a meteor shower. With this in mind, here’s a list of 10 places to see the meteor showers in the U.S., recommended by AccuWeather.

Want to know when to watch? Try EarthSky’s meteor shower guide for 2020

Got a great stargazing location to recommend? Recommend here

Try EarthSky’s Best Places to Stargaze page for lots more recommended dark sites.

Note: In 2020, some public parks are closed due to Covid-19. Be sure to check with these parks first, before you go.

1. Big Bend National Park, Texas. The world’s best places to see meteor showers are going to be untouched environments, such as national parks. Big Bend National Park in far west Texas has night skies that are nothing short of magical. It’s a great place to watch a meteor shower!

View larger. | Sergio Garcia Rill caught the Perseid meteor shower in Big Bend National Park in 2015. He wrote, “Well, here’s the result of a night at the Cerro Castellan area inside Big Bend. This photo has got 23 meteors in it, as well as me trying to find some shooting stars with my flashlight.” Thank you Sergio!

2. Joshua Tree National Park, California. Given the many densely populated cities in California, it’s hard to imagine that this state would have good sites to see meteor showers. But – like all states in the United States – it does. Beloved Joshua Tree National Park is one of the places in California to see stars and meteors.

Joan Schipper wrote: “The Sierra Club Camera Committee went to Joshua Tree National Park trying to catch some Orionid meteors in pixels. Eight of us were staked out in various locations at White Tank campground. This is my 3rd attempt to capture meteors and my 2nd bit of success.”

3. Death Valley, California/Nevada. Don’t let its name scare you. Straddling California and Nevada, Death Valley – with its naturally dark skies – is another hot spot for meteor showers and stargazing.

The 2018 Geminid meteor shower rains down on Death Valley, as seen from Zabriskie Point. Comet Wirtanen is visible in the upper left, below and to the left of Pleiades. Image via Rick Whitacre.

4. Finger Lakes, New York. Much like California, New York has densely populated areas. But New York has the beauty of the Finger Lakes for people to enjoy. Because Finger Lakes are located away from the bright lights of the city, its night skies provide an incredible view.

5. The area around Tucson, Arizona. This desert region is surrounded by tall hills and mountains, places where you can get up high to look at the sky.

Draconids near Tucson, Arizona, in 2013, by our friend Sean Parker Photography.

6. Denali National Park, Alaska. Generally speaking, Alaska is a place many would expect to find on this list. The state is full of natural beauty. That said, Denali National Park in Alaska is known for its dark skies.

7. Brockway Mountain, Michigan. A great place for stargazing and meteor-watching in the upper midwest.

8. Big Pine Key, Florida. If Alaska is an obvious candidate for seeing meteor showers, Florida might be the opposite. Yet Big Pine Key in Florida has an annual winter party for stargazing.

If you’re in Florida for stargazing, be sure to check with Cape Canaveral to see if there are any space launches you can watch, to add to your experience. Richard Benzinger in Crescent Beach, Florida, caught the March 16, 2017, SpaceX launch of Echostar XXIII from Cape Canaveral, shooting southeast. Thanks, Richard!

9. White Sands, New Mexico. While it is not as flat as Death Valley, White Sands is flat enough and dark enough to provide a great platform for meteor-watching.

10. Canyonlands National Park, Utah. Stargazing and meteor-watching under Utah’s glorious night skies … what could be better?

View larger. | Quinn Pratt caught this 2014 photo of night skies over Canyonlands National Park. Thank you, Quinn!

Bottom line: Ten recommended sites for watching meteor showers, from AccuWeather and the editors of EarthSky.

Want to know when to watch meteor showers? Try EarthSky’s meteor shower guide for 2020

Got a great stargazing location to recommend? Recommend here

Try EarthSky’s Best Places to Stargaze page for lots more recommended dark sites.

from EarthSky https://ift.tt/3g3zPnw

Asteroid Day, June 30, live from Luxembourg

Image via Debbie Lewis.

Originally published at AsteroidDay.org.

The Asteroid Foundation returns with Asteroid Day Live Digital from Luxembourg. This year, the event is a fully digital celebration of asteroid science and exploration. Panel discussions and one-on-one interviews with astronauts and world experts will be broadcast on June 30, 2020.

Asteroid Day Live is streaming over Asteroid Day TV, and the detailed program schedule can be found on the Asteroid Day website. Following Asteroid Day on June 30, the various panels will be available on that website, as well as on YouTube.

Asteroid Day is held on June 30 each year to mark the date of Earth’s largest asteroid impact in recorded history, the Siberia Tunguska event. Asteroid Day was co-founded by astrophysicist and famed musician Dr. Brian May of the rock group Queen, Apollo 9 astronaut Rusty Schweickart, filmmaker Grig Richters, and B612 Foundation President Danica Remy, to educate the public about the importance of asteroids in our history and the role they play in the solar system. In 2016, with the leadership of the Association of Space Explorers (ASE), the United Nations declared Asteroid Day to be a global day of education to raise awareness and promote knowledge in the general public about asteroids. For more information visit AsteroidDay.org.

Each year Asteroid Day presents the public with a snapshot of cutting-edge asteroid research from the largest telescopes on Earth to some of the most ambitious space missions. Topics of discussion this year include the acceleration in the rate of our asteroid discoveries and why it is set to accelerate even faster, the imminent arrival of samples from asteroid Ryugu and Bennu, the exciting preparations for the joint U.S.-Europe mission to binary asteroid Didymos, and much more.

Early in the morning on February 15, 2013, a small, previously unknown asteroid entered Earth’s atmosphere at 37,280 miles per hour (66,000 km/h) and exploded high above Chelyabinsk, Russia, with 20-30 times the energy of the Hiroshima atomic bomb. Photo via Alex Alishevskikh/ Flickr.

Asteroids are the leftover remnants of the birth of the planets in the solar system, and many are the shattered fragments of these diminutive proto-planets that never made it to maturity.

Tom Jones, Ph.D., veteran astronaut and planetary scientist, and Asteroid Day Expert Panel member, said:

Asteroid exploration missions tell us about the birth of our own planet and reveal how asteroids can serve astronauts as stepping stones to Mars.

Each asteroid is an individual with its own story to tell. And that’s what Asteroid Day is all about: bringing those stories to the widest audience possible.

Ruy Pinto, Chief Technology Officer at SES, said:

Space and science have been an endless source of inspiration for SES! This is one of the reasons why we and our partners continue to do extraordinary things in space to deliver amazing experiences everywhere on earth.

Through satellite broadcasting, we are able to reach millions of TV households and this enables us to unite people around science, space, and technology topics.

Mark Serres, the CEO of the Luxembourg Space Agency, said:

The valuable expertise of SES and BCE play a central role in making Asteroid Day an international success and enabling us to have a global conversation about space, space resources, and asteroids in these COVID-19 times.

Such studies can also protect our planet. European Space Agency (ESA) Director General Jan Wörner noted:

An asteroid impact is a natural disaster we might be able to avoid if we see one coming soon enough

Join Asteroid Day Live Digital from Luxembourg to celebrate the solar system’s magnificent debris.

Asteroid Day Live Digital from Luxembourg is a five-hour program with panel discussions including:

• Target Asteroid: How to Move an Incoming Space Rock
• Ingredients of Life: Bringing Asteroid Samples to Earth
• Asteroid Safari: Finding the Elusive Space Rocks
• Preparing the Future: Making Tools to Investigate Asteroids
• Seeing is Believing: The Art of Asteroid Computer Simulations
• From Satellites to Asteroids: Luxembourg’s and ESA’s Role
• Ask Me Anything About Asteroids with Astronauts

Panel hosts include Sarah Cruddas, Alan Boyle, Lisa Burke, Sabinije von Gaffke, and Stuart Clark. The panel summary descriptions can be found here.

In the week leading up to Asteroid Day, the European Space Agency will produce several Asteroid Day programs in French, Spanish, Dutch, German, and Italian including asteroid experts and special guests discussing European planetary defense and asteroid-related activities aimed at general audiences in those countries and ESA debuts an English segment on June 30 as part of Asteroid Day LIVE from Luxembourg.

In addition to the ESA programs, there are independent online talks taking place worldwide as well. “Stones Fallen From the Sky: The Birth of the Science of Asteroids and Meteorites” will come from Spain, and Asteroid Day Chile has organized for 20+ national institutions to give talks, workshops for children, and audiovisual segments. These will be broadcast on Facebook Live and YouTube simultaneously on June 29 and 30. These and more can be found online at asteroidday.org; only a limited number of independent events are possible this year due to Covid-19.

The story of Asteroid Day.

Bottom line: The 6th annual Asteroid Day will be held as a digital event on June 30, 2020. It’ll feature presentations with experts, panel discussions, and question-and-answer periods. Here’s how to participate.

Via AsteroidDay.org

from EarthSky https://ift.tt/2KDhe65

Image via Debbie Lewis.

Originally published at AsteroidDay.org.

The Asteroid Foundation returns with Asteroid Day Live Digital from Luxembourg. This year, the event is a fully digital celebration of asteroid science and exploration. Panel discussions and one-on-one interviews with astronauts and world experts will be broadcast on June 30, 2020.

Asteroid Day Live is streaming over Asteroid Day TV, and the detailed program schedule can be found on the Asteroid Day website. Following Asteroid Day on June 30, the various panels will be available on that website, as well as on YouTube.

Asteroid Day is held on June 30 each year to mark the date of Earth’s largest asteroid impact in recorded history, the Siberia Tunguska event. Asteroid Day was co-founded by astrophysicist and famed musician Dr. Brian May of the rock group Queen, Apollo 9 astronaut Rusty Schweickart, filmmaker Grig Richters, and B612 Foundation President Danica Remy, to educate the public about the importance of asteroids in our history and the role they play in the solar system. In 2016, with the leadership of the Association of Space Explorers (ASE), the United Nations declared Asteroid Day to be a global day of education to raise awareness and promote knowledge in the general public about asteroids. For more information visit AsteroidDay.org.

Each year Asteroid Day presents the public with a snapshot of cutting-edge asteroid research from the largest telescopes on Earth to some of the most ambitious space missions. Topics of discussion this year include the acceleration in the rate of our asteroid discoveries and why it is set to accelerate even faster, the imminent arrival of samples from asteroid Ryugu and Bennu, the exciting preparations for the joint U.S.-Europe mission to binary asteroid Didymos, and much more.

Early in the morning on February 15, 2013, a small, previously unknown asteroid entered Earth’s atmosphere at 37,280 miles per hour (66,000 km/h) and exploded high above Chelyabinsk, Russia, with 20-30 times the energy of the Hiroshima atomic bomb. Photo via Alex Alishevskikh/ Flickr.

Asteroids are the leftover remnants of the birth of the planets in the solar system, and many are the shattered fragments of these diminutive proto-planets that never made it to maturity.

Tom Jones, Ph.D., veteran astronaut and planetary scientist, and Asteroid Day Expert Panel member, said:

Asteroid exploration missions tell us about the birth of our own planet and reveal how asteroids can serve astronauts as stepping stones to Mars.

Each asteroid is an individual with its own story to tell. And that’s what Asteroid Day is all about: bringing those stories to the widest audience possible.

Ruy Pinto, Chief Technology Officer at SES, said:

Space and science have been an endless source of inspiration for SES! This is one of the reasons why we and our partners continue to do extraordinary things in space to deliver amazing experiences everywhere on earth.

Through satellite broadcasting, we are able to reach millions of TV households and this enables us to unite people around science, space, and technology topics.

Mark Serres, the CEO of the Luxembourg Space Agency, said:

The valuable expertise of SES and BCE play a central role in making Asteroid Day an international success and enabling us to have a global conversation about space, space resources, and asteroids in these COVID-19 times.

Such studies can also protect our planet. European Space Agency (ESA) Director General Jan Wörner noted:

An asteroid impact is a natural disaster we might be able to avoid if we see one coming soon enough

Join Asteroid Day Live Digital from Luxembourg to celebrate the solar system’s magnificent debris.

Asteroid Day Live Digital from Luxembourg is a five-hour program with panel discussions including:

• Target Asteroid: How to Move an Incoming Space Rock
• Ingredients of Life: Bringing Asteroid Samples to Earth
• Asteroid Safari: Finding the Elusive Space Rocks
• Preparing the Future: Making Tools to Investigate Asteroids
• Seeing is Believing: The Art of Asteroid Computer Simulations
• From Satellites to Asteroids: Luxembourg’s and ESA’s Role
• Ask Me Anything About Asteroids with Astronauts

Panel hosts include Sarah Cruddas, Alan Boyle, Lisa Burke, Sabinije von Gaffke, and Stuart Clark. The panel summary descriptions can be found here.

In the week leading up to Asteroid Day, the European Space Agency will produce several Asteroid Day programs in French, Spanish, Dutch, German, and Italian including asteroid experts and special guests discussing European planetary defense and asteroid-related activities aimed at general audiences in those countries and ESA debuts an English segment on June 30 as part of Asteroid Day LIVE from Luxembourg.

In addition to the ESA programs, there are independent online talks taking place worldwide as well. “Stones Fallen From the Sky: The Birth of the Science of Asteroids and Meteorites” will come from Spain, and Asteroid Day Chile has organized for 20+ national institutions to give talks, workshops for children, and audiovisual segments. These will be broadcast on Facebook Live and YouTube simultaneously on June 29 and 30. These and more can be found online at asteroidday.org; only a limited number of independent events are possible this year due to Covid-19.

The story of Asteroid Day.

Bottom line: The 6th annual Asteroid Day will be held as a digital event on June 30, 2020. It’ll feature presentations with experts, panel discussions, and question-and-answer periods. Here’s how to participate.

Via AsteroidDay.org

from EarthSky https://ift.tt/2KDhe65

More evidence that Europa’s ocean is habitable

Europa has many cracks in its otherwise smooth surface. Many believe the cracks are the result of the rising and falling of tides in a global ocean beneath Europa’s icy surface. A new study adds to the evidence that this subsurface ocean may be habitable. Image via NASA/ JPL-Caltech/ SETI Institute.

Is there life on Jupiter’s ocean moon Europa? This moon has fascinated space enthusiasts for decades, since scientists determined there’s a global ocean of water beneath the moon’s icy outer crust. Last week (June 24, 2020), NASA scientists announced new research that supports the idea that Europa’s ocean is habitable. They said this underground ocean is likely similar in many ways to the open-air oceans on Earth.

The fascinating results were presented at the Goldschmidt conference (virtual this year due to Covid-19). The associated abstract is available on the conference website. These are preliminary results, and not yet peer-reviewed.

First, the findings support what scientists had predicted about the composition of the ocean, as planetary scientist and lead researcher Mohit Melwani Daswani explained in a statement:

We were able to model the composition and physical properties of the core, silicate layer, and ocean. We find that different minerals lose water and volatiles at different depths and temperatures. We added up these volatiles that are estimated to have been lost from the interior, and found that they are consistent with the current ocean’s predicted mass, meaning that they are probably present in the ocean.

A cutaway illustrative view of Europa’s subsurface ocean. Image via NASA/ JPL-Caltech/ Sci-News.

To reach this conclusion, the researchers modeled geochemical reservoirs within the interior of Europa using data from the old Galileo mission. The results are significant since they show that oceans like the one on Europa can be formed by metamorphism, that is, by a change of minerals or a distinct arrangement of minerals (a change in what geologists call texture) in preexisting rocks (protoliths) without the protolith melting into liquid magma.

On Europa, heating and increased pressure caused by early radioactive decay or later subsurface tidal movement, would have caused a breakdown of water-containing minerals. Trapped water would be released, and Europa’s underground ocean would be born.

So what about habitability?

The study also found that Europa’s ocean would have been mildly acidic at first, with high concentrations of carbon dioxide, calcium and sulfate. But over time, it became chloride-rich, resembling oceans on Earth (seawater on Earth contains 1.94% chloride). According to Daswani:

Indeed it was thought that this ocean could still be rather sulfuric, but our simulations, coupled with data from the Hubble Space Telescope, showing chloride on Europa’s surface, suggests that the water most likely became chloride rich. In other words, its composition became more like oceans on Earth. We believe that this ocean could be quite habitable for life.

Europa is one of our best chances of finding life in our own solar system. NASA’s Europa Clipper mission will launch in the next few years, and so our work aims to prepare for the mission, which will investigate Europa’s habitability. Our models lead us to think that the oceans in other moons, such as Europa’s neighbor Ganymede, and Saturn’s moon Titan, may also have formed by similar processes.

We still need to understand several points though, such as how fluids migrate through Europa’s rocky interior.

Although not proven yet, there is growing evidence for water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus (artist’s concept). Image via ASA/ ESA/ K. Retherford/ SwRI/ Science.

Another interesting possibility is that volcanic vents on the seafloor of Europa’s ocean might have contributed to the process of the water’s becoming chloride-rich. That would be exciting, since such vents on Earth provide heat and nutrients to a wide variety of life in our world’s deep oceans.

The Cassini spacecraft has already found evidence for such vents on the seafloor of Saturn’s moon Enceladus, which also has a global ocean beneath its icy crust.

These or other energy sources would be necessary for life to evolve and thrive in an underground ocean: a dark and sunless environment. As Steve Mojzsis, Professor of Geology at the University of Colorado Boulder, noted:

A long-standing question over whether a ‘cloaked ocean’ world like Europa could be habitable boils down to whether it can sustain a flow of electrons which might provide the energy to power life. What remains unclear is whether such icy moons could ever generate enough heat to melt rock; certainly interesting chemistry takes place within these bodies, but what reliable flow of electrons could be used by alien life to power itself in the cold, dark depths?

A key aspect that makes a world ‘habitable’ is an intrinsic ability to maintain these chemical disequilibria. Arguably, icy moons lack this ability, so this needs to be tested on any future mission to Europa.

Jupiter’s ocean moon Europa, as seen by the Galileo spacecraft. This image is a combination of images from 1995 and 1998. Image via NASA/ JPL-Caltech/ SETI Institute.

The results of the new study are tantalizing, but more work needs to be done. How much chloride is really in Europa’s ocean? As mentioned in a June 25, 2020, article on Centauri Dreams, a paper from 2019 stated the following about sodium chloride (NaCl) on Europa:

The presence of NaCl on Europa has important implications for our understanding of the internal chemistry and its geochemical evolution through time. Whereas aqueous differentiation of chondritic material and long-term leaching from a chondritic seafloor can result in a system rich in sulfates, more extensive hydrothermal circulation, as on Earth, may lead to an NaCl-rich ocean. The plume chemistry of Enceladus, which is perhaps the best analog to Europa, suggests an NaCl-dominated ocean and a hydrothermally active seafloor. However, the compositional relationship between Europa’s ocean and its endogenous material is unknown, and the surface may simply represent the end result of a compositional stratification within the ice shell… Regardless of whether the observed NaCl directly relates to the ocean composition, its presence warrants a reevaluation of our understanding of the geochemistry of Europa.

Scientists can learn more about Europa’s ocean by modeling, but obtaining solid evidence will require actually sending a mission back there. Fortunately, NASA’s Europa Clipper mission is set to do just that, scheduled to launch in 2023.

Europa is one of the largest moons in the solar system with a diameter of 1,926 miles (3,100 km), just a little less than Earth’s moon. While the subsurface ocean is relatively warm (exact temperature not known yet), on the almost airless surface of Europa the temperatures are always a bitter minus 256 degrees Fahrenheit (minus 160 degrees Celsius) or lower.

Mohit Melwani Daswani, planetary scientist at NASA and lead author of the new study. Image via Jet Propulsion Laboratory (JPL).

There is also growing evidence for water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus. If they are there, Europa Clipper could fly through them, just as Cassini did at Enceladus, and sample the vapor for analysis. If connected to the ocean, as Enceladus’ are thought to be, that would provide valuable clues as to conditions in the Europan ocean and, maybe, even evidence of life itself.

The latest analysis of Europa’s ocean is tantalizing, but we will know a lot more after Europa Clipper – and ESA’s Jupiter Icy Moon Explorer (JUICE) mission – take a closer look in the years ahead.

Bottom line: New study by NASA scientists shows that Europa’s ocean is habitable.

Source: Evolution of volatiles from Europa’s interior into its ocean

Via Astrobiology Web

from EarthSky https://ift.tt/2AanyhM

Europa has many cracks in its otherwise smooth surface. Many believe the cracks are the result of the rising and falling of tides in a global ocean beneath Europa’s icy surface. A new study adds to the evidence that this subsurface ocean may be habitable. Image via NASA/ JPL-Caltech/ SETI Institute.

Is there life on Jupiter’s ocean moon Europa? This moon has fascinated space enthusiasts for decades, since scientists determined there’s a global ocean of water beneath the moon’s icy outer crust. Last week (June 24, 2020), NASA scientists announced new research that supports the idea that Europa’s ocean is habitable. They said this underground ocean is likely similar in many ways to the open-air oceans on Earth.

The fascinating results were presented at the Goldschmidt conference (virtual this year due to Covid-19). The associated abstract is available on the conference website. These are preliminary results, and not yet peer-reviewed.

First, the findings support what scientists had predicted about the composition of the ocean, as planetary scientist and lead researcher Mohit Melwani Daswani explained in a statement:

We were able to model the composition and physical properties of the core, silicate layer, and ocean. We find that different minerals lose water and volatiles at different depths and temperatures. We added up these volatiles that are estimated to have been lost from the interior, and found that they are consistent with the current ocean’s predicted mass, meaning that they are probably present in the ocean.

A cutaway illustrative view of Europa’s subsurface ocean. Image via NASA/ JPL-Caltech/ Sci-News.

To reach this conclusion, the researchers modeled geochemical reservoirs within the interior of Europa using data from the old Galileo mission. The results are significant since they show that oceans like the one on Europa can be formed by metamorphism, that is, by a change of minerals or a distinct arrangement of minerals (a change in what geologists call texture) in preexisting rocks (protoliths) without the protolith melting into liquid magma.

On Europa, heating and increased pressure caused by early radioactive decay or later subsurface tidal movement, would have caused a breakdown of water-containing minerals. Trapped water would be released, and Europa’s underground ocean would be born.

So what about habitability?

The study also found that Europa’s ocean would have been mildly acidic at first, with high concentrations of carbon dioxide, calcium and sulfate. But over time, it became chloride-rich, resembling oceans on Earth (seawater on Earth contains 1.94% chloride). According to Daswani:

Indeed it was thought that this ocean could still be rather sulfuric, but our simulations, coupled with data from the Hubble Space Telescope, showing chloride on Europa’s surface, suggests that the water most likely became chloride rich. In other words, its composition became more like oceans on Earth. We believe that this ocean could be quite habitable for life.

Europa is one of our best chances of finding life in our own solar system. NASA’s Europa Clipper mission will launch in the next few years, and so our work aims to prepare for the mission, which will investigate Europa’s habitability. Our models lead us to think that the oceans in other moons, such as Europa’s neighbor Ganymede, and Saturn’s moon Titan, may also have formed by similar processes.

We still need to understand several points though, such as how fluids migrate through Europa’s rocky interior.

Although not proven yet, there is growing evidence for water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus (artist’s concept). Image via ASA/ ESA/ K. Retherford/ SwRI/ Science.

Another interesting possibility is that volcanic vents on the seafloor of Europa’s ocean might have contributed to the process of the water’s becoming chloride-rich. That would be exciting, since such vents on Earth provide heat and nutrients to a wide variety of life in our world’s deep oceans.

The Cassini spacecraft has already found evidence for such vents on the seafloor of Saturn’s moon Enceladus, which also has a global ocean beneath its icy crust.

These or other energy sources would be necessary for life to evolve and thrive in an underground ocean: a dark and sunless environment. As Steve Mojzsis, Professor of Geology at the University of Colorado Boulder, noted:

A long-standing question over whether a ‘cloaked ocean’ world like Europa could be habitable boils down to whether it can sustain a flow of electrons which might provide the energy to power life. What remains unclear is whether such icy moons could ever generate enough heat to melt rock; certainly interesting chemistry takes place within these bodies, but what reliable flow of electrons could be used by alien life to power itself in the cold, dark depths?

A key aspect that makes a world ‘habitable’ is an intrinsic ability to maintain these chemical disequilibria. Arguably, icy moons lack this ability, so this needs to be tested on any future mission to Europa.

Jupiter’s ocean moon Europa, as seen by the Galileo spacecraft. This image is a combination of images from 1995 and 1998. Image via NASA/ JPL-Caltech/ SETI Institute.

The results of the new study are tantalizing, but more work needs to be done. How much chloride is really in Europa’s ocean? As mentioned in a June 25, 2020, article on Centauri Dreams, a paper from 2019 stated the following about sodium chloride (NaCl) on Europa:

The presence of NaCl on Europa has important implications for our understanding of the internal chemistry and its geochemical evolution through time. Whereas aqueous differentiation of chondritic material and long-term leaching from a chondritic seafloor can result in a system rich in sulfates, more extensive hydrothermal circulation, as on Earth, may lead to an NaCl-rich ocean. The plume chemistry of Enceladus, which is perhaps the best analog to Europa, suggests an NaCl-dominated ocean and a hydrothermally active seafloor. However, the compositional relationship between Europa’s ocean and its endogenous material is unknown, and the surface may simply represent the end result of a compositional stratification within the ice shell… Regardless of whether the observed NaCl directly relates to the ocean composition, its presence warrants a reevaluation of our understanding of the geochemistry of Europa.

Scientists can learn more about Europa’s ocean by modeling, but obtaining solid evidence will require actually sending a mission back there. Fortunately, NASA’s Europa Clipper mission is set to do just that, scheduled to launch in 2023.

Europa is one of the largest moons in the solar system with a diameter of 1,926 miles (3,100 km), just a little less than Earth’s moon. While the subsurface ocean is relatively warm (exact temperature not known yet), on the almost airless surface of Europa the temperatures are always a bitter minus 256 degrees Fahrenheit (minus 160 degrees Celsius) or lower.

Mohit Melwani Daswani, planetary scientist at NASA and lead author of the new study. Image via Jet Propulsion Laboratory (JPL).

There is also growing evidence for water vapor plumes on Europa, similar to those on Saturn’s moon Enceladus. If they are there, Europa Clipper could fly through them, just as Cassini did at Enceladus, and sample the vapor for analysis. If connected to the ocean, as Enceladus’ are thought to be, that would provide valuable clues as to conditions in the Europan ocean and, maybe, even evidence of life itself.

The latest analysis of Europa’s ocean is tantalizing, but we will know a lot more after Europa Clipper – and ESA’s Jupiter Icy Moon Explorer (JUICE) mission – take a closer look in the years ahead.

Bottom line: New study by NASA scientists shows that Europa’s ocean is habitable.

Source: Evolution of volatiles from Europa’s interior into its ocean

Via Astrobiology Web

from EarthSky https://ift.tt/2AanyhM