Every visible star is within Milky Way

The image at top, showing a campfire under the Milky Way, is a classic, from 2014. It’s by Ben Coffman Photography in Oregon. He had written:

These good folks – co-workers from one of the resorts on Mt. Hood, if I remember correctly – let me take their photo on the beach near Cape Kiwanda [a state natural area near in Pacific City, Oregon]. They looked like they were having fun.

And so they do. What could be better than a beautiful night under the Milky Way? But did you know that every night of your life is a night under the Milky Way? By that we mean … every individual star you can see with the unaided eye, in all parts of the sky, lies within the confines of our Milky Way galaxy.

Our galaxy – seen in Ben’s photo above as a bright and hazy band of stars – is estimated to be some 100,000 light-years wide and only about 1,000 light-years thick. That’s why the starlit band of the Milky Way, which is still visible in the evening this month but will soon be less so, appears so well-defined in our sky.

Gazing into it, we’re really looking edgewise into the thin plane of our own galaxy:

This image is mosaic of multiple shots on large-format film. It comprises all 360 degrees of the galaxy from our earthly vantage point. Photography was done in Ft. Davis, Texas for the northern hemisphere shots and from Broken Hill, New South Wales, Australia, for the southern portions. Note the dust lanes, which obscure our view of some features beyond them. Image via Digital Sky LLC

In the image directly above – comprising all 360 degrees of the galaxy as seen from our earthly vantage point – note that the galaxy is brightest at its center, where most of the stars and a 4-million-solar-mass black hole reside. This image shows stars down to 11th magnitude – fainter than the eye alone can see.

If you’re standing under a clear, dark night sky, you’ll see the Milky Way clearly as a band of stars stretched across the sky on late summer evenings.

The band of the Milky Way is tough to see unless you’re far from the artificial lights of the city and you’re looking on a night when the moon is down.

If you do look in a dark country sky, you’ll easily spot the Milky Way. And, assuming you’re looking from the Northern Hemisphere, you’ll notice that it gets broader and richer in the southern part of the sky, in the direction of the constellations Scorpius and Sagittarius. This is the direction toward the galaxy’s center.

If you’re in the Southern Hemisphere, the galactic center is still in the direction of Sagittarius. But from the southern part of Earth’s globe, this constellation is closer to overhead.

The image below gives you an idea of the awesome beauty of our Milky Way galaxy in the night sky.

Bottom line: If you look in a dark country sky, you’ll easily spot the starlit band of our huge, flat Milky Way galaxy. Every star in our night sky that’s visible to the unaided eye lies inside this galaxy.

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky planisphere from our store.

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The image at top, showing a campfire under the Milky Way, is a classic, from 2014. It’s by Ben Coffman Photography in Oregon. He had written:

These good folks – co-workers from one of the resorts on Mt. Hood, if I remember correctly – let me take their photo on the beach near Cape Kiwanda [a state natural area near in Pacific City, Oregon]. They looked like they were having fun.

And so they do. What could be better than a beautiful night under the Milky Way? But did you know that every night of your life is a night under the Milky Way? By that we mean … every individual star you can see with the unaided eye, in all parts of the sky, lies within the confines of our Milky Way galaxy.

Our galaxy – seen in Ben’s photo above as a bright and hazy band of stars – is estimated to be some 100,000 light-years wide and only about 1,000 light-years thick. That’s why the starlit band of the Milky Way, which is still visible in the evening this month but will soon be less so, appears so well-defined in our sky.

Gazing into it, we’re really looking edgewise into the thin plane of our own galaxy:

This image is mosaic of multiple shots on large-format film. It comprises all 360 degrees of the galaxy from our earthly vantage point. Photography was done in Ft. Davis, Texas for the northern hemisphere shots and from Broken Hill, New South Wales, Australia, for the southern portions. Note the dust lanes, which obscure our view of some features beyond them. Image via Digital Sky LLC

In the image directly above – comprising all 360 degrees of the galaxy as seen from our earthly vantage point – note that the galaxy is brightest at its center, where most of the stars and a 4-million-solar-mass black hole reside. This image shows stars down to 11th magnitude – fainter than the eye alone can see.

If you’re standing under a clear, dark night sky, you’ll see the Milky Way clearly as a band of stars stretched across the sky on late summer evenings.

The band of the Milky Way is tough to see unless you’re far from the artificial lights of the city and you’re looking on a night when the moon is down.

If you do look in a dark country sky, you’ll easily spot the Milky Way. And, assuming you’re looking from the Northern Hemisphere, you’ll notice that it gets broader and richer in the southern part of the sky, in the direction of the constellations Scorpius and Sagittarius. This is the direction toward the galaxy’s center.

If you’re in the Southern Hemisphere, the galactic center is still in the direction of Sagittarius. But from the southern part of Earth’s globe, this constellation is closer to overhead.

The image below gives you an idea of the awesome beauty of our Milky Way galaxy in the night sky.

Bottom line: If you look in a dark country sky, you’ll easily spot the starlit band of our huge, flat Milky Way galaxy. Every star in our night sky that’s visible to the unaided eye lies inside this galaxy.

A planisphere is virtually indispensable for beginning stargazers. Order your EarthSky planisphere from our store.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Donate: Your support means the world to us

from EarthSky https://ift.tt/2m2Eobw

The launch and landing of China’s reusable spacecraft

No images have yet been released of China’s September 4, 2020 rocket launch. This image shows a launch in October 2016 of a Chinese Long March 2F rocket, the same rocket model that launched a new, experimental, reusable spacecraft. Image via China Aerospace Science and Technology Corporation.

China is widely believed to have launched and landed a reusable spacecraft late last week, which might have deployed a satellite while in orbit. Chinese media outlet Xinhua News reported on September 6, 2020 that a Long March-2F rocket sent the experimental spacecraft into orbit on September 4 from the Gobi Desert Jiuquan Satellite Launch Center, and that the craft touched down as scheduled after a two-day in-orbit operation. The Xinhau report provided no information about exact launch time, landing location, or what technologies the spacecraft tested. It said:

The reusable spacecraft successfully launched by my country at the Jiuquan Satellite Launch Center successfully returned to the scheduled landing site on September 6, after flying in orbit for 2 days.

The successful flight marked the country’s important breakthrough in reusable spacecraft research, and is expected to offer convenient and low-cost round-trip transport for the peaceful use of the space.

The new spacecraft may be linked with China’s plans to build and operate a reusable space plane by the year 2020, although that connection has not been confirmed.

China calls the new spacecraft Chongfu Shiyong Shiyan Hangtian Qi, which translates as Repeat-Use Test Spacecraft (or, more loosely, Reusable Test Spacecraft).

Analysis by space experts show a object in space that wasn’t there before the September 4 launch. The analysis suggests that the Chinese spacecraft released a satellite while in orbit, although the satellite’s purpose is pure speculation, as neither Chinese nor United States space-tracking organizations have released details.

Interesting! A new object (2020-063G, nr 46395) has been catalogued, in a 332 x 348 km orbit. My analysis suggests it was ejected from China's experimental spacecraft near 22:25 UT on the 5th, about two revolutions before landing.
(HT to @planet4589 for noting the extra object)

— Dr Marco Langbroek (@Marco_Langbroek) September 6, 2020

Likewise, China has not so far released images of the spacecraft or the launch; an apparent higher-than-usual level of security surrounding the mission also prevented bystander images from appearing on social media. These precautions are widely said in the west to be “unusual,” given China’s assurance that the intention of the mission is peaceful.

Xinhua had reported in 2017 that China was planning a reusable space vehicle that would take off and land horizontally, like an airplane. In fact, officials from the China Aerospace Science and Industry Corporation added in 2017 that it had already fulfilled several ground tests for engines and other components, for such a craft. But Harvard-Smithsonian Center for Astrophysics astronomer Jonathan McDowell (@planet4589 on Twitter) – who comments frequently on the spacecraft program – has stressed that we cannot assume the spacecraft launched September 4 is a space plane, with wings.

***BUT***
– "reusable" doesn't necessarily mean "winged".
– still *could* be a Dragon style capsule with a parachute landing in the Taklamakan somewhere
– exact launch and landing times not announced by China
So we should be clear about what is known and what is a guess.

— Jonathan McDowell (@planet4589) September 6, 2020

Other winged vehicles have made it to orbit previously. For example, NASA’s now-retired space shuttle program flew 135 missions with astronauts onboard between 1981 and 2011. A similarly reusable Soviet Union vehicle called Buran flew a single uncrewed mission in 1988 before the program was canceled in 1993, shortly after the Soviet Union collapsed.

In the present era, in the U.S., private companies are working hard to develop and test space planes and reusable rocketry. Virgin Galactic’s suborbital SpaceShipTwo has flown into space during test missions, which aims to fly customers and cargo aboard in the coming years. Similarly, the Sierra Nevada Corporation plans to fly NASA cargo to the International Space Station on its Dream Chaser spacecraft. Competitors like SpaceX and Blue Origin are making headlines every week for their record-setting accomplishments with fully reusable space vehicles.

Meanwhile, there’s already a rocket graveyard at the bottom of Earth’s ocean, littered with the exhausted shells of thousands of rockets used to send satellites and people to space. It’s humbling to contemplate these relics of a past age, but also important to notice that the lack of reusable rocket technology restricts space flight to the richest nations only.

Now, with the evolution of reusable rockets through such commercial companies, the price tag on space exploration and utilization is decreasing. The recent milestones of the U.S. private space companies – perhaps in conjunction with China’s Reusable Test Spacecraft – may be acting as a gateway of opportunity for interplanetary transport and the first manned mission to Mars.

Bottom line: Although few details are known, and no images have been released, the Chinese did apparently launch a reusable spacecraft on September 4, 2020. It appears to have deployed a satellite to orbit and then returned to Earth safely 2 days later.

Read more from Space News: Chinese Reusable Experimental Spacecraft Releases Object Before Returning to Earth

Read more from Discovery.com: Reusable Rockets: Expanding Space Exploration Possibilities with Retrievable Spacecraft.

Read more from Cosmos Magazine: Reusable Rockets Explained

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

No images have yet been released of China’s September 4, 2020 rocket launch. This image shows a launch in October 2016 of a Chinese Long March 2F rocket, the same rocket model that launched a new, experimental, reusable spacecraft. Image via China Aerospace Science and Technology Corporation.

China is widely believed to have launched and landed a reusable spacecraft late last week, which might have deployed a satellite while in orbit. Chinese media outlet Xinhua News reported on September 6, 2020 that a Long March-2F rocket sent the experimental spacecraft into orbit on September 4 from the Gobi Desert Jiuquan Satellite Launch Center, and that the craft touched down as scheduled after a two-day in-orbit operation. The Xinhau report provided no information about exact launch time, landing location, or what technologies the spacecraft tested. It said:

The reusable spacecraft successfully launched by my country at the Jiuquan Satellite Launch Center successfully returned to the scheduled landing site on September 6, after flying in orbit for 2 days.

The successful flight marked the country’s important breakthrough in reusable spacecraft research, and is expected to offer convenient and low-cost round-trip transport for the peaceful use of the space.

The new spacecraft may be linked with China’s plans to build and operate a reusable space plane by the year 2020, although that connection has not been confirmed.

China calls the new spacecraft Chongfu Shiyong Shiyan Hangtian Qi, which translates as Repeat-Use Test Spacecraft (or, more loosely, Reusable Test Spacecraft).

Analysis by space experts show a object in space that wasn’t there before the September 4 launch. The analysis suggests that the Chinese spacecraft released a satellite while in orbit, although the satellite’s purpose is pure speculation, as neither Chinese nor United States space-tracking organizations have released details.

Interesting! A new object (2020-063G, nr 46395) has been catalogued, in a 332 x 348 km orbit. My analysis suggests it was ejected from China's experimental spacecraft near 22:25 UT on the 5th, about two revolutions before landing.
(HT to @planet4589 for noting the extra object)

— Dr Marco Langbroek (@Marco_Langbroek) September 6, 2020

Likewise, China has not so far released images of the spacecraft or the launch; an apparent higher-than-usual level of security surrounding the mission also prevented bystander images from appearing on social media. These precautions are widely said in the west to be “unusual,” given China’s assurance that the intention of the mission is peaceful.

Xinhua had reported in 2017 that China was planning a reusable space vehicle that would take off and land horizontally, like an airplane. In fact, officials from the China Aerospace Science and Industry Corporation added in 2017 that it had already fulfilled several ground tests for engines and other components, for such a craft. But Harvard-Smithsonian Center for Astrophysics astronomer Jonathan McDowell (@planet4589 on Twitter) – who comments frequently on the spacecraft program – has stressed that we cannot assume the spacecraft launched September 4 is a space plane, with wings.

***BUT***
– "reusable" doesn't necessarily mean "winged".
– still *could* be a Dragon style capsule with a parachute landing in the Taklamakan somewhere
– exact launch and landing times not announced by China
So we should be clear about what is known and what is a guess.

— Jonathan McDowell (@planet4589) September 6, 2020

Other winged vehicles have made it to orbit previously. For example, NASA’s now-retired space shuttle program flew 135 missions with astronauts onboard between 1981 and 2011. A similarly reusable Soviet Union vehicle called Buran flew a single uncrewed mission in 1988 before the program was canceled in 1993, shortly after the Soviet Union collapsed.

In the present era, in the U.S., private companies are working hard to develop and test space planes and reusable rocketry. Virgin Galactic’s suborbital SpaceShipTwo has flown into space during test missions, which aims to fly customers and cargo aboard in the coming years. Similarly, the Sierra Nevada Corporation plans to fly NASA cargo to the International Space Station on its Dream Chaser spacecraft. Competitors like SpaceX and Blue Origin are making headlines every week for their record-setting accomplishments with fully reusable space vehicles.

Meanwhile, there’s already a rocket graveyard at the bottom of Earth’s ocean, littered with the exhausted shells of thousands of rockets used to send satellites and people to space. It’s humbling to contemplate these relics of a past age, but also important to notice that the lack of reusable rocket technology restricts space flight to the richest nations only.

Now, with the evolution of reusable rockets through such commercial companies, the price tag on space exploration and utilization is decreasing. The recent milestones of the U.S. private space companies – perhaps in conjunction with China’s Reusable Test Spacecraft – may be acting as a gateway of opportunity for interplanetary transport and the first manned mission to Mars.

Bottom line: Although few details are known, and no images have been released, the Chinese did apparently launch a reusable spacecraft on September 4, 2020. It appears to have deployed a satellite to orbit and then returned to Earth safely 2 days later.

Read more from Space News: Chinese Reusable Experimental Spacecraft Releases Object Before Returning to Earth

Read more from Discovery.com: Reusable Rockets: Expanding Space Exploration Possibilities with Retrievable Spacecraft.

Read more from Cosmos Magazine: Reusable Rockets Explained

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

2020 is your year to see Capricornus

This chart works for September 9 or 10, 2020 … and for lots of nights after that, approximately through late September. Chart via Guy Ottewell’s blog.

Originally published at Guy Ottewell’s blog. Reprinted here with permission.

Above is a chart showing the night sky on Wednesday, September 9, 2020. See how Jupiter and Saturn are pointing to the constellation Capricornus the Sea Goat? You need a dark sky to see this constellation, but Jupiter and Saturn are very bright. If you have that dark sky, and have never seen this faint constellation, now is the time to look.

Below you’ll find is an example of the unhelpful sky charts generally used in the astronomy columns of newspapers and popular magazines.

It’s from Sunday’s Guardian. The article rightly says that Capricornus is an important constellation because it is part of the ancient zodiac, but it is inconspicuous, and you can at present use Jupiter and Saturn as pointers to it.

Chart via The Guardian.

Fair enough. But the chart doesn’t do Capricornus justice. Perhaps you, sage reader, can with effort decipher the Guardian’s chart because you know the sky. But, if you were a beginner, could you use this maze of dots and lines to find anything as you gaze at the sky? I don’t think so.

I think the way of connecting dots is derived from H.A. Rey’s ingenious but doomed method as described in his book “The Stars: A New Way to See Them.” It tries to make Capricornus look like a goat. But Capricornus doesn’t look like a goat; it looks like a boat, or – as the Americans prefer – an arrowhead.

I hope my way of rendering this part of the sky – as seen on the chart at the top of the post – is more helpful.

Read more about the constellation Capricornus

Chart via Posts That Look Like Science. Thanks for pointing it out, David Terry Dorais!

Bottom line: In 2020, the bright planets Jupiter and Saturn can help you find the faint constellation Capricornus the Sea Goat.

from EarthSky https://ift.tt/2ZktSg2

This chart works for September 9 or 10, 2020 … and for lots of nights after that, approximately through late September. Chart via Guy Ottewell’s blog.

Originally published at Guy Ottewell’s blog. Reprinted here with permission.

Above is a chart showing the night sky on Wednesday, September 9, 2020. See how Jupiter and Saturn are pointing to the constellation Capricornus the Sea Goat? You need a dark sky to see this constellation, but Jupiter and Saturn are very bright. If you have that dark sky, and have never seen this faint constellation, now is the time to look.

Below you’ll find is an example of the unhelpful sky charts generally used in the astronomy columns of newspapers and popular magazines.

It’s from Sunday’s Guardian. The article rightly says that Capricornus is an important constellation because it is part of the ancient zodiac, but it is inconspicuous, and you can at present use Jupiter and Saturn as pointers to it.

Chart via The Guardian.

Fair enough. But the chart doesn’t do Capricornus justice. Perhaps you, sage reader, can with effort decipher the Guardian’s chart because you know the sky. But, if you were a beginner, could you use this maze of dots and lines to find anything as you gaze at the sky? I don’t think so.

I think the way of connecting dots is derived from H.A. Rey’s ingenious but doomed method as described in his book “The Stars: A New Way to See Them.” It tries to make Capricornus look like a goat. But Capricornus doesn’t look like a goat; it looks like a boat, or – as the Americans prefer – an arrowhead.

I hope my way of rendering this part of the sky – as seen on the chart at the top of the post – is more helpful.

Read more about the constellation Capricornus

Chart via Posts That Look Like Science. Thanks for pointing it out, David Terry Dorais!

Bottom line: In 2020, the bright planets Jupiter and Saturn can help you find the faint constellation Capricornus the Sea Goat.

from EarthSky https://ift.tt/2ZktSg2

See Messier 20, the Trifid Nebula

Visible light pictures show the nebula divided into 3 parts by dark, obscuring dust lanes, but this penetrating infrared image by the Spitzer Space Telescope reveals filaments of luminous gas and newborn stars. Image via APOD/ JPL-Caltech/ J. Rho (SSC/Caltech)

The Trifid Nebula (Messier 20 or M20) is one of the many binocular treasures in the direction of the center of our Milky Way galaxy. Its name means divided into three lobes, although you’ll likely need a telescope to see why. On a dark, moonless night – from a rural location – you can star-hop upward from the spout of the Teapot in Sagittarius to another famous nebula, the Lagoon, also known as Messier 8. In the same binocular field, look for the smaller and fainter Trifid Nebula as a fuzzy patch above the Lagoon.

To locate this nebula, first find the famous Teapot asterism in the western half of Sagittarius. The Teapot is just a star pattern, not an entire constellation. Nonetheless, most people have an easier time envisioning the Teapot than the Centaur that Sagittarius is supposed to represent. How can you find it? First, be sure you’re looking on a dark night, from a rural location.

Then, look for southward in the evening from Earth’s Northern Hemisphere. If you’re in Earth’s Southern Hemisphere, look northward, closer to overhead, and turn the charts below upside-down. Want a more exact location for the Teapot in Sagittarius? We hear good things about Stellarium, which will let you set a date and time from your exact location on the globe.

You’ll find M20 in a dark sky near the spout of the Teapot in Sagittarius. Notice the 3 westernmost (right-hand) stars of the Teapot spout … then get ready to star-hop! Use binoculars and go about twice the spout’s distance upward until a bright hazy object glares at you in your binoculars. That’s the Lagoon Nebula (Messier 8), which is actually visible to the unaided eye on a dark, moonless night. Once you locate the Lagoon Nebula, look for the smaller Trifid Nebula as a hazy object some 2 degrees above the Lagoon. For reference, keep in mind that a binocular field commonly spans 5 to 6 degrees of sky. Here’s more about the Teapot.

Chart showing one of the most star-rich regions of the Milky Way galaxy, toward the galaxy’s center, in the direction of the constellation Sagittarius. If you look closely, you can pick out M20 on this chart. Chart via astronomy.com.

Whether the close-knit nebulosity of the Trifid and the Lagoon represents a chance alignment or an actual kinship between the two nebulae is open to question. Both the Trifid and Lagoon are thought to reside about 5,000 light-years away, suggesting the possibility of a common origin. But these distances are not known with precision, and may be subject to revision.

Both the Trifid and Lagoon are vast cocoons of interstellar dust and gas. These are stellar nurseries, actively giving birth to new stars. The Trifid and Lagoon Nebulae are a counterpart to another star-forming region on the opposite side of the sky: the Great Orion Nebula.

Trifid Nebula via the Hubble Space Telescope. Image via NASA/ESA.

The Trifid Nebula (M20) is at RA: 18h 02.6s; Dec: -23^o 02′

Bottom line: The Trifid nebula (M20) is located in the direction of the center of the Milky Way galaxy. If you have an extremely dark sky, you can see the nebula on a moonless night as a fuzzy patch in the Milky Way. Binoculars show more … and a telescope still more.

Read more: Find the Teapot, and look toward the galaxy’s center

Read more: M8 is the Lagoon Nebula

Read more: Exploring the Trifid Nebula

from EarthSky https://ift.tt/2Zhe4vH

Visible light pictures show the nebula divided into 3 parts by dark, obscuring dust lanes, but this penetrating infrared image by the Spitzer Space Telescope reveals filaments of luminous gas and newborn stars. Image via APOD/ JPL-Caltech/ J. Rho (SSC/Caltech)

The Trifid Nebula (Messier 20 or M20) is one of the many binocular treasures in the direction of the center of our Milky Way galaxy. Its name means divided into three lobes, although you’ll likely need a telescope to see why. On a dark, moonless night – from a rural location – you can star-hop upward from the spout of the Teapot in Sagittarius to another famous nebula, the Lagoon, also known as Messier 8. In the same binocular field, look for the smaller and fainter Trifid Nebula as a fuzzy patch above the Lagoon.

To locate this nebula, first find the famous Teapot asterism in the western half of Sagittarius. The Teapot is just a star pattern, not an entire constellation. Nonetheless, most people have an easier time envisioning the Teapot than the Centaur that Sagittarius is supposed to represent. How can you find it? First, be sure you’re looking on a dark night, from a rural location.

Then, look for southward in the evening from Earth’s Northern Hemisphere. If you’re in Earth’s Southern Hemisphere, look northward, closer to overhead, and turn the charts below upside-down. Want a more exact location for the Teapot in Sagittarius? We hear good things about Stellarium, which will let you set a date and time from your exact location on the globe.

You’ll find M20 in a dark sky near the spout of the Teapot in Sagittarius. Notice the 3 westernmost (right-hand) stars of the Teapot spout … then get ready to star-hop! Use binoculars and go about twice the spout’s distance upward until a bright hazy object glares at you in your binoculars. That’s the Lagoon Nebula (Messier 8), which is actually visible to the unaided eye on a dark, moonless night. Once you locate the Lagoon Nebula, look for the smaller Trifid Nebula as a hazy object some 2 degrees above the Lagoon. For reference, keep in mind that a binocular field commonly spans 5 to 6 degrees of sky. Here’s more about the Teapot.

Chart showing one of the most star-rich regions of the Milky Way galaxy, toward the galaxy’s center, in the direction of the constellation Sagittarius. If you look closely, you can pick out M20 on this chart. Chart via astronomy.com.

Whether the close-knit nebulosity of the Trifid and the Lagoon represents a chance alignment or an actual kinship between the two nebulae is open to question. Both the Trifid and Lagoon are thought to reside about 5,000 light-years away, suggesting the possibility of a common origin. But these distances are not known with precision, and may be subject to revision.

Both the Trifid and Lagoon are vast cocoons of interstellar dust and gas. These are stellar nurseries, actively giving birth to new stars. The Trifid and Lagoon Nebulae are a counterpart to another star-forming region on the opposite side of the sky: the Great Orion Nebula.

Trifid Nebula via the Hubble Space Telescope. Image via NASA/ESA.

The Trifid Nebula (M20) is at RA: 18h 02.6s; Dec: -23^o 02′

Bottom line: The Trifid nebula (M20) is located in the direction of the center of the Milky Way galaxy. If you have an extremely dark sky, you can see the nebula on a moonless night as a fuzzy patch in the Milky Way. Binoculars show more … and a telescope still more.

Read more: Find the Teapot, and look toward the galaxy’s center

Read more: M8 is the Lagoon Nebula

Read more: Exploring the Trifid Nebula

from EarthSky https://ift.tt/2Zhe4vH

Use the Big Dipper to find the North Star

Tonight’s chart shows Polaris and the Big and Little Dippers for a September evening. You can use the Big Dipper to find Polaris, which is also known as the North Star. Notice that a line from the two outermost stars in the bowl of the Big Dipper points to Polaris. And notice that Polaris marks the tip of the handle of the Little Dipper.

The northern sky is a large clock, with Polaris at its center. The hour hand is a line drawn through Dubhe and Merak, the two pointer stars of the Big Dipper. Because the stars make a full circle in 23 hours 56 minutes instead of exactly 24 hours, this star clock is not exactly the same as the one on the wall, but with a little practice you can learn to read it well.

The Big Dipper swings full circle – 360 degrees – around Polaris in about 23 hours and 56 minutes. In 24 hours, the Big Dipper actually swings more than a full circle, or 361 degrees. Does that make a difference? Yes! It means that – if you look at the same time each evening – the Big Dipper will appear just a little bit lower in the northwestern evening sky.

If you’re in the northern U.S., Canada or at a similar latitude, the Big Dipper is circumpolar for you – always above the horizon. Image via burro.astr.cwru.edu

A month from now at mid-evening, the Big Dipper will be noticeably lower in the northwest. It’ll be actually beneath the horizon as seen from the southern latitudes in the United States – although it’s circumpolar, or always above the northern horizon, as seen from the northern U.S., Canada and similarly northern latitudes.

The constant motion from night to night of these stars circling Polaris is a bit like a bear circling its prey, looking for a way to attack. Several ancient cultures from the Greeks and Romans to the Mi?kmaq Indians likened these stars to a bear.

In Greek mythology, the Big Dipper asterism represents the hindquarters and tail of the constellation Ursa Major, the Great Bear. The Mi?kmaq saw the three stars of the Big Dipper handle as hunters chasing the bear.

Watch the Big and Little Dippers circle around Polaris tonight!

Bottom line: To locate Polaris, the North Star, just draw a line between the two outer stars in the bowl of the Big Dipper.

The Big and Little Dippers: All you need to know

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

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Tonight’s chart shows Polaris and the Big and Little Dippers for a September evening. You can use the Big Dipper to find Polaris, which is also known as the North Star. Notice that a line from the two outermost stars in the bowl of the Big Dipper points to Polaris. And notice that Polaris marks the tip of the handle of the Little Dipper.

The northern sky is a large clock, with Polaris at its center. The hour hand is a line drawn through Dubhe and Merak, the two pointer stars of the Big Dipper. Because the stars make a full circle in 23 hours 56 minutes instead of exactly 24 hours, this star clock is not exactly the same as the one on the wall, but with a little practice you can learn to read it well.

The Big Dipper swings full circle – 360 degrees – around Polaris in about 23 hours and 56 minutes. In 24 hours, the Big Dipper actually swings more than a full circle, or 361 degrees. Does that make a difference? Yes! It means that – if you look at the same time each evening – the Big Dipper will appear just a little bit lower in the northwestern evening sky.

If you’re in the northern U.S., Canada or at a similar latitude, the Big Dipper is circumpolar for you – always above the horizon. Image via burro.astr.cwru.edu

A month from now at mid-evening, the Big Dipper will be noticeably lower in the northwest. It’ll be actually beneath the horizon as seen from the southern latitudes in the United States – although it’s circumpolar, or always above the northern horizon, as seen from the northern U.S., Canada and similarly northern latitudes.

The constant motion from night to night of these stars circling Polaris is a bit like a bear circling its prey, looking for a way to attack. Several ancient cultures from the Greeks and Romans to the Mi?kmaq Indians likened these stars to a bear.

In Greek mythology, the Big Dipper asterism represents the hindquarters and tail of the constellation Ursa Major, the Great Bear. The Mi?kmaq saw the three stars of the Big Dipper handle as hunters chasing the bear.

Watch the Big and Little Dippers circle around Polaris tonight!

Bottom line: To locate Polaris, the North Star, just draw a line between the two outer stars in the bowl of the Big Dipper.

The Big and Little Dippers: All you need to know

EarthSky astronomy kits are perfect for beginners. Order today from the EarthSky store

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Last quarter moon is September 10

View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines, caught the last quarter moon shortly after it rose around midnight on the morning of September 22, 2019. This moon phase is perfect for helping you envision the location of the sun … below your feet. Thanks, Dr Ski!

September’s last quarter moon falls on Thursday, September 10, at 09:25 UTC (4:25 a.m. CDT). Translate UTC to your time.

A last quarter moon appears half-lit by sunshine and half-immersed in its own shadow. It rises in the middle of the night, appears at its highest in the sky around dawn, and sets around midday.

A last quarter moon provides a great opportunity to think of yourself on a three-dimensional world in space. Watch for this moon just after moonrise, shortly after midnight. Then the lighted portion points downward, to the sun below your feet. Think of the last quarter moon as a mirror to the world you’re standing on. Think of yourself standing in the midst of Earth’s nightside, on the midnight portion of Earth.

Click here to see animation. As seen from the north side of the moon’s orbital plane, the Earth rotates counterclockwise on its rotational axis, and the moon revolves counterclockwise around Earth. The terminators of the Earth and moon align at first and last quarter moons, and only the near half of the moon’s day side is visible from Earth.

On a last quarter moon, the lunar terminator – the shadow line dividing day and night – shows you where it’s sunset on the moon.

View at EarthSky Community Photos. | September 22, 2019, photo by Dr Ski. He wrote: “The moon’s southern limb at last quarter. The Straight Wall is either black or white depending on the angle of the sun’s rays. At lunar sunset (now), it’s white. Around full moon, Tycho is one of the easiest craters to find due to the impact rays emanating from it. It’s like the hub of a spoked wheel! At last quarter, Tycho becomes unremarkable. Clavius, on the other hand, becomes remarkable at high magnification.”

View at EarthSky Community Photos. | September 22, 2019, photo by Dr Ski. He wrote: “The Sea of Rains at last quarter. The lunar Alps and Apennines are bisected by the moon’s meridian. You can get an idea of the height of these mountains by how far they extend into the dark side of the terminator. At an elevation of over 5,000 meters [16,000 feet], the Apennines are twice as tall as the Alps.”

Also, a last quarter moon can be used as a guidepost to Earth’s direction of motion in orbit around the sun.

In other words, when you look toward a last quarter moon high in the predawn sky, for example, you’re gazing out approximately along the path of Earth’s orbit, in a forward direction. The moon is moving in orbit around the sun with the Earth and never holds still. But, if we could somehow anchor the moon in space … tie it down, keep it still … Earth’s orbital speed of 18 miles per second (29 km/sec) would carry us across the space between us and the moon in only a few hours.

Want to read more about the last quarter moon as a guidepost for Earth’s motion? Astronomer Guy Ottewell talks about it here.

A great thing about using the moon as a guidepost to Earth’s motion is that you can do it anywhere … as, for example, in the photo below, from large cities.

Ben Orlove wrote from New York City: “I was sitting in the roof garden of my building, and there was the moon, right in front of me. You were right, this is a perfect time to visualize … the Earth’s motion.”

As the moon orbits Earth, it changes phase in an orderly way. Read more: 4 keys to understanding moon phases

Bottom line: The moon reaches its last quarter phase on September 10, 2020, at 09:25 UTC. In the coming week, watch for the moon to rise in the east in the hours after midnight, waning thinner each morning.

from EarthSky https://ift.tt/2ze0n1D

View at EarthSky Community Photos. | Dr Ski in Valencia, Philippines, caught the last quarter moon shortly after it rose around midnight on the morning of September 22, 2019. This moon phase is perfect for helping you envision the location of the sun … below your feet. Thanks, Dr Ski!

September’s last quarter moon falls on Thursday, September 10, at 09:25 UTC (4:25 a.m. CDT). Translate UTC to your time.

A last quarter moon appears half-lit by sunshine and half-immersed in its own shadow. It rises in the middle of the night, appears at its highest in the sky around dawn, and sets around midday.

A last quarter moon provides a great opportunity to think of yourself on a three-dimensional world in space. Watch for this moon just after moonrise, shortly after midnight. Then the lighted portion points downward, to the sun below your feet. Think of the last quarter moon as a mirror to the world you’re standing on. Think of yourself standing in the midst of Earth’s nightside, on the midnight portion of Earth.

Click here to see animation. As seen from the north side of the moon’s orbital plane, the Earth rotates counterclockwise on its rotational axis, and the moon revolves counterclockwise around Earth. The terminators of the Earth and moon align at first and last quarter moons, and only the near half of the moon’s day side is visible from Earth.

On a last quarter moon, the lunar terminator – the shadow line dividing day and night – shows you where it’s sunset on the moon.

View at EarthSky Community Photos. | September 22, 2019, photo by Dr Ski. He wrote: “The moon’s southern limb at last quarter. The Straight Wall is either black or white depending on the angle of the sun’s rays. At lunar sunset (now), it’s white. Around full moon, Tycho is one of the easiest craters to find due to the impact rays emanating from it. It’s like the hub of a spoked wheel! At last quarter, Tycho becomes unremarkable. Clavius, on the other hand, becomes remarkable at high magnification.”

View at EarthSky Community Photos. | September 22, 2019, photo by Dr Ski. He wrote: “The Sea of Rains at last quarter. The lunar Alps and Apennines are bisected by the moon’s meridian. You can get an idea of the height of these mountains by how far they extend into the dark side of the terminator. At an elevation of over 5,000 meters [16,000 feet], the Apennines are twice as tall as the Alps.”

Also, a last quarter moon can be used as a guidepost to Earth’s direction of motion in orbit around the sun.

In other words, when you look toward a last quarter moon high in the predawn sky, for example, you’re gazing out approximately along the path of Earth’s orbit, in a forward direction. The moon is moving in orbit around the sun with the Earth and never holds still. But, if we could somehow anchor the moon in space … tie it down, keep it still … Earth’s orbital speed of 18 miles per second (29 km/sec) would carry us across the space between us and the moon in only a few hours.

Want to read more about the last quarter moon as a guidepost for Earth’s motion? Astronomer Guy Ottewell talks about it here.

A great thing about using the moon as a guidepost to Earth’s motion is that you can do it anywhere … as, for example, in the photo below, from large cities.

Ben Orlove wrote from New York City: “I was sitting in the roof garden of my building, and there was the moon, right in front of me. You were right, this is a perfect time to visualize … the Earth’s motion.”

As the moon orbits Earth, it changes phase in an orderly way. Read more: 4 keys to understanding moon phases

Bottom line: The moon reaches its last quarter phase on September 10, 2020, at 09:25 UTC. In the coming week, watch for the moon to rise in the east in the hours after midnight, waning thinner each morning.

from EarthSky https://ift.tt/2ze0n1D

It’s time to start watching Mars

View at EarthSky Community Photos. | Eliot Herman captured this dramatic view of Mars this past weekend, when it was near the moon: “Moon and Mars clearing the ridgeline in Tucson, Arizona. The close conjunction of the moon and bright near-opposition Mars was a striking sight. The terminator of the moon shows the terrain picking up light on the craters and mountains leading to the observed discontinuities [the jagged appearance of the upper edge of the moon].” Thank you, Eliot! See more photos of last weekend’s moon and Mars.

In the year 2018, Mars was brighter than all the stars. It was even brighter than the second-brightest planet, Jupiter. It was a blazing red dot of flame in our night sky for several months. In 2019, Mars was mostly faint. It was barely noticeable in our sky. And now Mars is bright again, brighter than all the stars. It’s not as bright as Jupiter yet, but it will be soon, for about a month surrounding mid-October 2020. Why? Why is Mars bright in some years, but faint in others? And why is Mars brightening so dramatically again now? Keep reading to learn why the appearance of Mars varies so widely in our sky, making Mars one of the most interesting planets to watch! Most importantly, learn how to start watching Mars now, so you can enjoy it for the remainder of this year.

September 2020 is a wonderful time to start watching Mars. It’s rising in the east now not long after the sun goes down. You can’t fail to recognize Mars. It’s very bright, and it’s very red in color. As the weeks go by, Mars will be rising earlier. By mid-October, it’ll be rising in the east as the sun sets in the west. After that, for the remainder of this year, Mars will be in our sky at sunset, fading in brightness as the year draws to a close, but still … a sight to see. To learn how to find Mars in the coming months, bookmark EarthSky’s planet guide.

More than any other bright planet, the appearance of Mars in our night sky changes from year to year. Its dramatic swings in brightness are part of the reason the early stargazers named Mars for their god of war; sometimes, the war god rests, and sometimes he grows fierce! Mars was bright in 2018 and faint again for most of 2019.

Now Mars is bright again.

Mars isn’t very big, so its brightness – when it is bright – isn’t due to its bigness, as is true of Jupiter. Mars’ brightness, or lack of brightness, is all about how close we are to the red planet. It’s all about where Earth and Mars are, relative to each other, in their respective orbits around the sun. Image via Lunar and Planetary Institute.

Why? Why does Mars sometimes appear very bright, and sometimes very faint?

The first thing to realize is that Mars isn’t a very big world. It’s only 4,219 miles (6,790 km) in diameter, making it only slightly more than half Earth’s size (7,922 miles or 12,750 km in diameter).

The small size of Mars is your first clue to its varying brightness. The small size means that, when Mars is bright, its brightness isn’t due to bigness, as is the case with the largest planet in our solar system, Jupiter.

Instead, the main reason for Mars’ extremes in brightness has to do with its nearness (or lack of nearness) to Earth.

Matt Pollack captured Mars from Little Tupper Lake in the Adirondacks of upstate New York in July 2018. Read more about this photo.

Mars orbits the sun one step outward from Earth. The distances between Earth and Mars change as both worlds orbit around the sun. Sometimes Earth and Mars are on the same side of the solar system, and hence near one another. At other times, as it was for much of 2017 and was again for much of 2019, Mars was moving on the opposite side of the solar system from Earth.

Look at the diagrams below, which show Earth and Mars in their respective orbits around the sun in mid-2018 and this month, June 2020 … and then in October 2020, when Earth and Mars will be closest for this two-year period.

This chart shows the relative positions of Earth (blue) and Mars (red) at the time of Mars’ coming opposition on October 13, 2020. Around that time, Mars will appear bright in our sky again – and in the sky all night long – but it won’t be as bright as it was in 2018. Image via Fourmilab.

Earth takes a year to orbit the sun once. Mars takes about two years to orbit once. Opposition for Mars – when Earth passes between Mars and the sun – happens every two years and 50 days.

So Mars’ brightness waxes and wanes in our sky about every two years. Because of this, 2018 was a very, very special year for Mars, when the planet was brighter than it had been since 2003. Astronomers called it a perihelic opposition (or perihelic apparition) of Mars. In other words, in 2018, we went between Mars and the sun – bringing Mars to opposition in our sky – around the same time Mars came closest to the sun. The word perihelion refers to Mars’ closest point to the sun in orbit.

Maybe you can see that – in years when we pass between Mars and the sun, when Mars is also closest to the sun – Earth and Mars are closest. That’s what happened in 2018.

2003 was the previous perihelic opposition for Mars. The red planet came within 34.6 million miles (55.7 million km) of Earth, closer than at any time in over nearly 60,000 years! That was really something.

There’s a 15-year cycle of Mars, whereby the red planet is brighter and fainter at opposition. In July 2018, we were at the peak of the 2-year cycle – and the peak of the 15-year cycle – and Mars was very, very bright! In 2020, we’re at the peak of the 2-year cycle, and Earth and Mars are farther apart at Mars’ opposition than they were in 2018. Still, 2020’s opposition of Mars is excellent. Diagram by Roy L. Bishop. Copyright Royal Astronomical Society of Canada. Used with permission. Visit the RASC estore to purchase the Observer’s Handbook, a necessary tool for all skywatchers. Read more about this image.

And now? Earth will pass between Mars and the sun next on October 13, 2020. The red planet will appear brightest in our sky – very bright indeed and fiery red – around that time.

And thus Mars alternates years in being bright in our sky, or faint. 2019 was a dull year, but 2020 is an exciting one, for Mars!

Now is the time to start watching Mars. When you spot it, keep your eye on its, and enjoy its growing brightness. And think what’s causing the brightness change: our own Earth, rushing along in our smaller, faster orbit, trying to catch up.

Watch for Mars!

Artist’s concept of Earth (3rd planet from the sun) passing between the sun and Mars (4th planet from the sun). Not to scale. This is Mars’ opposition, when it appears opposite the sun in our sky. Image via NASA.

Bottom line: Mars alternates years in appearing bright and faint in our night sky. In 2018, our view of Mars was the best since 2003! In 2019, we were in one of Mars’ faint years. But 2020 has brought another bright year for Mars. If you start watching Mars in September 2020, you can see it at its best and enjoy it for the remaining months of this year.

Photos of bright Mars in 2018, from the EarthSky community

from EarthSky https://ift.tt/2Puo0em

View at EarthSky Community Photos. | Eliot Herman captured this dramatic view of Mars this past weekend, when it was near the moon: “Moon and Mars clearing the ridgeline in Tucson, Arizona. The close conjunction of the moon and bright near-opposition Mars was a striking sight. The terminator of the moon shows the terrain picking up light on the craters and mountains leading to the observed discontinuities [the jagged appearance of the upper edge of the moon].” Thank you, Eliot! See more photos of last weekend’s moon and Mars.

In the year 2018, Mars was brighter than all the stars. It was even brighter than the second-brightest planet, Jupiter. It was a blazing red dot of flame in our night sky for several months. In 2019, Mars was mostly faint. It was barely noticeable in our sky. And now Mars is bright again, brighter than all the stars. It’s not as bright as Jupiter yet, but it will be soon, for about a month surrounding mid-October 2020. Why? Why is Mars bright in some years, but faint in others? And why is Mars brightening so dramatically again now? Keep reading to learn why the appearance of Mars varies so widely in our sky, making Mars one of the most interesting planets to watch! Most importantly, learn how to start watching Mars now, so you can enjoy it for the remainder of this year.

September 2020 is a wonderful time to start watching Mars. It’s rising in the east now not long after the sun goes down. You can’t fail to recognize Mars. It’s very bright, and it’s very red in color. As the weeks go by, Mars will be rising earlier. By mid-October, it’ll be rising in the east as the sun sets in the west. After that, for the remainder of this year, Mars will be in our sky at sunset, fading in brightness as the year draws to a close, but still … a sight to see. To learn how to find Mars in the coming months, bookmark EarthSky’s planet guide.

More than any other bright planet, the appearance of Mars in our night sky changes from year to year. Its dramatic swings in brightness are part of the reason the early stargazers named Mars for their god of war; sometimes, the war god rests, and sometimes he grows fierce! Mars was bright in 2018 and faint again for most of 2019.

Now Mars is bright again.

Mars isn’t very big, so its brightness – when it is bright – isn’t due to its bigness, as is true of Jupiter. Mars’ brightness, or lack of brightness, is all about how close we are to the red planet. It’s all about where Earth and Mars are, relative to each other, in their respective orbits around the sun. Image via Lunar and Planetary Institute.

Why? Why does Mars sometimes appear very bright, and sometimes very faint?

The first thing to realize is that Mars isn’t a very big world. It’s only 4,219 miles (6,790 km) in diameter, making it only slightly more than half Earth’s size (7,922 miles or 12,750 km in diameter).

The small size of Mars is your first clue to its varying brightness. The small size means that, when Mars is bright, its brightness isn’t due to bigness, as is the case with the largest planet in our solar system, Jupiter.

Instead, the main reason for Mars’ extremes in brightness has to do with its nearness (or lack of nearness) to Earth.

Matt Pollack captured Mars from Little Tupper Lake in the Adirondacks of upstate New York in July 2018. Read more about this photo.

Mars orbits the sun one step outward from Earth. The distances between Earth and Mars change as both worlds orbit around the sun. Sometimes Earth and Mars are on the same side of the solar system, and hence near one another. At other times, as it was for much of 2017 and was again for much of 2019, Mars was moving on the opposite side of the solar system from Earth.

Look at the diagrams below, which show Earth and Mars in their respective orbits around the sun in mid-2018 and this month, June 2020 … and then in October 2020, when Earth and Mars will be closest for this two-year period.

This chart shows the relative positions of Earth (blue) and Mars (red) at the time of Mars’ coming opposition on October 13, 2020. Around that time, Mars will appear bright in our sky again – and in the sky all night long – but it won’t be as bright as it was in 2018. Image via Fourmilab.

Earth takes a year to orbit the sun once. Mars takes about two years to orbit once. Opposition for Mars – when Earth passes between Mars and the sun – happens every two years and 50 days.

So Mars’ brightness waxes and wanes in our sky about every two years. Because of this, 2018 was a very, very special year for Mars, when the planet was brighter than it had been since 2003. Astronomers called it a perihelic opposition (or perihelic apparition) of Mars. In other words, in 2018, we went between Mars and the sun – bringing Mars to opposition in our sky – around the same time Mars came closest to the sun. The word perihelion refers to Mars’ closest point to the sun in orbit.

Maybe you can see that – in years when we pass between Mars and the sun, when Mars is also closest to the sun – Earth and Mars are closest. That’s what happened in 2018.

2003 was the previous perihelic opposition for Mars. The red planet came within 34.6 million miles (55.7 million km) of Earth, closer than at any time in over nearly 60,000 years! That was really something.

There’s a 15-year cycle of Mars, whereby the red planet is brighter and fainter at opposition. In July 2018, we were at the peak of the 2-year cycle – and the peak of the 15-year cycle – and Mars was very, very bright! In 2020, we’re at the peak of the 2-year cycle, and Earth and Mars are farther apart at Mars’ opposition than they were in 2018. Still, 2020’s opposition of Mars is excellent. Diagram by Roy L. Bishop. Copyright Royal Astronomical Society of Canada. Used with permission. Visit the RASC estore to purchase the Observer’s Handbook, a necessary tool for all skywatchers. Read more about this image.

And now? Earth will pass between Mars and the sun next on October 13, 2020. The red planet will appear brightest in our sky – very bright indeed and fiery red – around that time.

And thus Mars alternates years in being bright in our sky, or faint. 2019 was a dull year, but 2020 is an exciting one, for Mars!

Now is the time to start watching Mars. When you spot it, keep your eye on its, and enjoy its growing brightness. And think what’s causing the brightness change: our own Earth, rushing along in our smaller, faster orbit, trying to catch up.

Watch for Mars!

Artist’s concept of Earth (3rd planet from the sun) passing between the sun and Mars (4th planet from the sun). Not to scale. This is Mars’ opposition, when it appears opposite the sun in our sky. Image via NASA.

Bottom line: Mars alternates years in appearing bright and faint in our night sky. In 2018, our view of Mars was the best since 2003! In 2019, we were in one of Mars’ faint years. But 2020 has brought another bright year for Mars. If you start watching Mars in September 2020, you can see it at its best and enjoy it for the remaining months of this year.

Photos of bright Mars in 2018, from the EarthSky community

from EarthSky https://ift.tt/2Puo0em