North Taurid meteors to peak in moonlight

The long-last North Taurid meteor shower may reach its annual peak from around late evening on November 11, 2019, until the wee morning hours on November 12. Unlike some meteor showers, though, the North Taurids don’t exhibit a sharp peak, so the meteor rates may remain fairly steady throughout the coming week. Now here’s the bad news. The North Taurids are peaking this under the glaring light of the full moon, which comes on November 12.

In a dark sky, you might see as many as 5 meteors per hour. In a moonlit sky … we can’t estimate precisely, but you might see a few.

This shower favors the Northern Hemisphere, but no matter where you live worldwide, the best viewing hours are usually in the wee hours just after midnight. The year, as the shower peaks in 2019, moon will be up high and shining mightily around the midnight hour, bleaching out these meteors. A high percentage of Taurid meteors do tend to be fireballs, or especially bright meteors. Let’s hope a few Taurid fireballs can overcome the moonlight!

November 2019 guide to the five visible planets

One of 32 constellation cards in Urania’s Mirror (View of the Heavens), via ianridpath.com.

The North Taurid meteors derive their name from the constellation Taurus the Bull. If you trace the paths of the Taurid meteors backward, you’ll see they appear to radiate from near the famous Pleiades star cluster of this constellation on the peak nights of the North Taurid meteor shower.

You don’t have to find Taurus, though, to watch the North Taurid meteors. These slow-moving meteors can light up any part of the starry heavens, streaking through a wide variety of constellations.

So just lie back comfortably and gaze in all parts of the sky, while waiting for the Taurid meteors.

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

Taurid meteor seen by Ken Christison in Conway, North Carolina on November 8, 2012. See the V-shaped face of the Bull in Taurus, and the very bright planet Jupiter nearby?

On a moonless night, a dark sky highlights the Bull – the radiant point for the North Taurid meteors – in all his starlit majesty. Taurus contains many noticeable stars – plus two star clusters – and is pretty easy to spot. The Bull appears over the eastern horizon by around 8 p.m. and is highest up in the sky around 1 a.m.

The Bull’s face consists of a V-shaped star cluster called the Hyades cluster. The Bull’s fiery red eye – the star Aldebaran – is not part of the Hyades. This ruddy star lies in the same direction, though at only about half the distance to the Hyades cluster.

The star Elnath marks the tip of the Bull’s northern horn.

And the Pleiades star cluster marks the Bull’s shoulder.

The radiant point of this shower soars to his highest point for the night around 12:30 a.m. local time. That’s why the meteors are best around then.

Taurus descends westward throughout the morning hours, and is found over the western horizon by daybreak.

Meteor flies by constellation Orion. At top left of photo, planet Jupiter and star Aldebaran highlight constellation Taurus, near the radiant point of this weekend’s meteor shower. Allen Lefever captured this meteor in November 2012.

Bottom line: The year 2019 finds the slow-moving North Taurid meteors having to compete with moonlight, as this shower reaches its peak on the night of November 11-12.

Read more: Full moon subdues North Taurid meteor shower peak

from EarthSky https://ift.tt/36La3R8

The long-last North Taurid meteor shower may reach its annual peak from around late evening on November 11, 2019, until the wee morning hours on November 12. Unlike some meteor showers, though, the North Taurids don’t exhibit a sharp peak, so the meteor rates may remain fairly steady throughout the coming week. Now here’s the bad news. The North Taurids are peaking this under the glaring light of the full moon, which comes on November 12.

In a dark sky, you might see as many as 5 meteors per hour. In a moonlit sky … we can’t estimate precisely, but you might see a few.

This shower favors the Northern Hemisphere, but no matter where you live worldwide, the best viewing hours are usually in the wee hours just after midnight. The year, as the shower peaks in 2019, moon will be up high and shining mightily around the midnight hour, bleaching out these meteors. A high percentage of Taurid meteors do tend to be fireballs, or especially bright meteors. Let’s hope a few Taurid fireballs can overcome the moonlight!

November 2019 guide to the five visible planets

One of 32 constellation cards in Urania’s Mirror (View of the Heavens), via ianridpath.com.

The North Taurid meteors derive their name from the constellation Taurus the Bull. If you trace the paths of the Taurid meteors backward, you’ll see they appear to radiate from near the famous Pleiades star cluster of this constellation on the peak nights of the North Taurid meteor shower.

You don’t have to find Taurus, though, to watch the North Taurid meteors. These slow-moving meteors can light up any part of the starry heavens, streaking through a wide variety of constellations.

So just lie back comfortably and gaze in all parts of the sky, while waiting for the Taurid meteors.

Easily locate stars and constellations during any day and time with EarthSky’s Planisphere.

Taurid meteor seen by Ken Christison in Conway, North Carolina on November 8, 2012. See the V-shaped face of the Bull in Taurus, and the very bright planet Jupiter nearby?

On a moonless night, a dark sky highlights the Bull – the radiant point for the North Taurid meteors – in all his starlit majesty. Taurus contains many noticeable stars – plus two star clusters – and is pretty easy to spot. The Bull appears over the eastern horizon by around 8 p.m. and is highest up in the sky around 1 a.m.

The Bull’s face consists of a V-shaped star cluster called the Hyades cluster. The Bull’s fiery red eye – the star Aldebaran – is not part of the Hyades. This ruddy star lies in the same direction, though at only about half the distance to the Hyades cluster.

The star Elnath marks the tip of the Bull’s northern horn.

And the Pleiades star cluster marks the Bull’s shoulder.

The radiant point of this shower soars to his highest point for the night around 12:30 a.m. local time. That’s why the meteors are best around then.

Taurus descends westward throughout the morning hours, and is found over the western horizon by daybreak.

Meteor flies by constellation Orion. At top left of photo, planet Jupiter and star Aldebaran highlight constellation Taurus, near the radiant point of this weekend’s meteor shower. Allen Lefever captured this meteor in November 2012.

Bottom line: The year 2019 finds the slow-moving North Taurid meteors having to compete with moonlight, as this shower reaches its peak on the night of November 11-12.

Read more: Full moon subdues North Taurid meteor shower peak

from EarthSky https://ift.tt/36La3R8

News digest – transforming radiotherapy research, ‘DIY’ cervical screening tests, exercise and UK General Election

£56m to revolutionise radiotherapy research in the UK

A new network of experts has been charged with developing the next generation of radiotherapy treatments. Our £56 million investment, which was widely reported, looks to transform the UK into a global research hub, pioneering the use of innovative new techniques in radiotherapy and artificial intelligence (AI) to improve therapy. Read more about how we intend to revolutionise radiotherapy in our blog post.

‘DIY’ home tests could provide new options for cervical screening

A new ‘DIY’ urine or swab test that can be done at home could provide an alternative to current cervical screening tests, reports the BBC. It’s an exciting prospect, as tests like these can help to improve early detection and break down barriers to attending cervical screening. But while the tests could pick up DNA changes caused by HPV infection, the major cause of pre-cancerous cervical cell changes, they’re not ready to be rolled out just yet. So far, only people with advanced cervical cell changes that were picked up through existing screening tests have been studied. Researchers will now need to test how effective the kits are for more people, including those who’ve had normal screening results before.

Gut bacteria may be linked to increased bowel cancer risk

The Guardian reported a study showing a certain type of gut bacteria could increase the risk of bowel cancer by up to 15% in some people. The study, yet to be published, looked at the genetic and microbiome data of 120,000 people to see whether people with certain genetic traits had a greater risk of developing the disease. But experts have been quick to urge caution when interpreting the results, saying it’s difficult to judge how strong the findings are without more information. The role that the bugs in our gut play in cancer is getting more and more attention, read our blog post for a closer look at the microbiome.

Added benefits of exercise for breast cancer patients revealed

New research suggests that people with breast cancer who exercise for the recommended 150 minutes each week could help reduce their risk of dying. The study, picked up by Mail Online, was run by scientists at the German Cancer Research Centre and involved over 2,000 women. But while there’s evidence emerging that exercise can help improve survival, more research needs to be done to understand which types of exercises are most helpful, and when they might make a difference. Experts recommended that anyone considering taking up exercise alongside their treatment should speak to their doctor first.

High-risk men should get prostate cancer checks, says researchers

Scientists in London say an annual blood test should be recommended to men born at high risk of developing prostate cancer. But while understanding more about people at higher risk of prostate cancer is important, previous studies have shown that PSA is not a suitable test for screening prostate cancer in the general population. And there’s still a lot more work to do before we can say that giving PSA tests to high-risk men could save lives from this disease.  Read the story at BBC News.

Excitement over blood test that detects breast cancer ‘years before symptoms develop’

‘Simple’ blood tests were back in the news this week after early results from a study by researchers in Nottingham, presented at a conference, suggest that breast cancer can be detected in the blood up to 5 years before clinical signs. But while the potential of detecting cancers markers in the blood is hugely promising, the test detected less than 4 in 10 cancers in patients who had already been diagnosed.

Only children are more likely to be obese than those with siblings

A US study has found that only children are significantly more likely to be overweight by the time they turn 7. Research suggests 37% of only children are obese, compared with just 5% of children with siblings. Whilst the reasons behind these findings are unclear, scientists reported unhealthier eating habits and the higher weight of mothers in only children as potential reasons. But as the study only monitored 68 children over a one-week period, there’s a lot more to learn before scientists can say if this is a true link and what could reduce children’s risk of developing obesity as a result. Find the full write-up in the Mail Online.

Vitamin D makes melanoma cells less aggressive in the lab

Scientists have uncovered more about how vitamin D influences the behaviour of melanoma cells in the lab and in mice. While it’s early days yet, scientists hope to use this information to investigate if vitamin D could one-day help to boost the effectiveness of other treatments.  Our press release gives more insight on the study.

New AI blood test could speed up diagnosis of brain tumours

iNews reports on a new test, which combines blood tests with an artificial intelligence (AI) programme, that could speed up the diagnosis of brain tumours and help patients receive treatment earlier. Researchers trialled the new test on blood samples from 400 people with possible signs of brain tumour, 40 of whom were subsequently found to have the disease. The test correctly identified 82% of the brain tumours. The next step is to try the test in 600 people who are suspected of having a brain tumour.

First steps taken in editing genes to fight cancer

Doctors in the US have begun testing a new gene-editing technique for people with cancer. The editing was done by a DNA snipping tool called CRISPR, editing genes to help patients’ immune systems attack cancer cells. So far, the treatment has been trialled in 3 patients, with the main aim to asses if the treatment is safe to use in people. The New York Times has more.

And finally…

Campaigns have kicked off for the UK General Election on the 12^thDecember. Use our General Election fact checker to help you see all party claims about cancer in the run up to elections.

Scarlett Sangster is a writer for PA Media Group 

from Cancer Research UK – Science blog https://ift.tt/2CvLdXm

£56m to revolutionise radiotherapy research in the UK

A new network of experts has been charged with developing the next generation of radiotherapy treatments. Our £56 million investment, which was widely reported, looks to transform the UK into a global research hub, pioneering the use of innovative new techniques in radiotherapy and artificial intelligence (AI) to improve therapy. Read more about how we intend to revolutionise radiotherapy in our blog post.

‘DIY’ home tests could provide new options for cervical screening

A new ‘DIY’ urine or swab test that can be done at home could provide an alternative to current cervical screening tests, reports the BBC. It’s an exciting prospect, as tests like these can help to improve early detection and break down barriers to attending cervical screening. But while the tests could pick up DNA changes caused by HPV infection, the major cause of pre-cancerous cervical cell changes, they’re not ready to be rolled out just yet. So far, only people with advanced cervical cell changes that were picked up through existing screening tests have been studied. Researchers will now need to test how effective the kits are for more people, including those who’ve had normal screening results before.

Gut bacteria may be linked to increased bowel cancer risk

The Guardian reported a study showing a certain type of gut bacteria could increase the risk of bowel cancer by up to 15% in some people. The study, yet to be published, looked at the genetic and microbiome data of 120,000 people to see whether people with certain genetic traits had a greater risk of developing the disease. But experts have been quick to urge caution when interpreting the results, saying it’s difficult to judge how strong the findings are without more information. The role that the bugs in our gut play in cancer is getting more and more attention, read our blog post for a closer look at the microbiome.

Added benefits of exercise for breast cancer patients revealed

New research suggests that people with breast cancer who exercise for the recommended 150 minutes each week could help reduce their risk of dying. The study, picked up by Mail Online, was run by scientists at the German Cancer Research Centre and involved over 2,000 women. But while there’s evidence emerging that exercise can help improve survival, more research needs to be done to understand which types of exercises are most helpful, and when they might make a difference. Experts recommended that anyone considering taking up exercise alongside their treatment should speak to their doctor first.

High-risk men should get prostate cancer checks, says researchers

Scientists in London say an annual blood test should be recommended to men born at high risk of developing prostate cancer. But while understanding more about people at higher risk of prostate cancer is important, previous studies have shown that PSA is not a suitable test for screening prostate cancer in the general population. And there’s still a lot more work to do before we can say that giving PSA tests to high-risk men could save lives from this disease.  Read the story at BBC News.

Excitement over blood test that detects breast cancer ‘years before symptoms develop’

‘Simple’ blood tests were back in the news this week after early results from a study by researchers in Nottingham, presented at a conference, suggest that breast cancer can be detected in the blood up to 5 years before clinical signs. But while the potential of detecting cancers markers in the blood is hugely promising, the test detected less than 4 in 10 cancers in patients who had already been diagnosed.

Only children are more likely to be obese than those with siblings

A US study has found that only children are significantly more likely to be overweight by the time they turn 7. Research suggests 37% of only children are obese, compared with just 5% of children with siblings. Whilst the reasons behind these findings are unclear, scientists reported unhealthier eating habits and the higher weight of mothers in only children as potential reasons. But as the study only monitored 68 children over a one-week period, there’s a lot more to learn before scientists can say if this is a true link and what could reduce children’s risk of developing obesity as a result. Find the full write-up in the Mail Online.

Vitamin D makes melanoma cells less aggressive in the lab

Scientists have uncovered more about how vitamin D influences the behaviour of melanoma cells in the lab and in mice. While it’s early days yet, scientists hope to use this information to investigate if vitamin D could one-day help to boost the effectiveness of other treatments.  Our press release gives more insight on the study.

New AI blood test could speed up diagnosis of brain tumours

iNews reports on a new test, which combines blood tests with an artificial intelligence (AI) programme, that could speed up the diagnosis of brain tumours and help patients receive treatment earlier. Researchers trialled the new test on blood samples from 400 people with possible signs of brain tumour, 40 of whom were subsequently found to have the disease. The test correctly identified 82% of the brain tumours. The next step is to try the test in 600 people who are suspected of having a brain tumour.

First steps taken in editing genes to fight cancer

Doctors in the US have begun testing a new gene-editing technique for people with cancer. The editing was done by a DNA snipping tool called CRISPR, editing genes to help patients’ immune systems attack cancer cells. So far, the treatment has been trialled in 3 patients, with the main aim to asses if the treatment is safe to use in people. The New York Times has more.

And finally…

Campaigns have kicked off for the UK General Election on the 12^thDecember. Use our General Election fact checker to help you see all party claims about cancer in the run up to elections.

Scarlett Sangster is a writer for PA Media Group 

from Cancer Research UK – Science blog https://ift.tt/2CvLdXm

Transit of Mercury on November 11, 2019

Photo at top: Mercury transit, May 9, 2016 via @altair_astro on Twitter. See more photos of the 2016 Mercury transit.

Mercury – the innermost planet of our solar system – will transit the sun on November 11, 2019. In other words, Mercury will pass directly in front of the sun and be visible through telescopes with solar filters as a small black dot crossing the sun’s face. It’ll be visible in part from most of Earth’s globe. The entire transit is visible from South America, eastern North America, and far-western Africa.

The last transit of Mercury was in 2016. The next one won’t be until 2032.

Mercury will come into view on the sun’s face around 7:36 a.m. Eastern Standard Time (12:36 UTC; translate UTC to your time) on November 11. It’ll make a leisurely journey across the sun’s face, reaching greatest transit (closest to sun’s center) at approximately 10:20 a.m. EST (15:20 UTC) and finally exiting around 1:04 p.m. EST (18:04 UTC). The entire 5 1/2 hour path across the sun will be visible across the U.S. East – with magnification and proper solar filters – while those in the U.S. West can observe the transit already in progress after sunrise.

Translate UTC to your time

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

You need a telescope and solar filters to view the transit. Mercury’s diameter is only 1/194th of that of the sun, as seen from Earth. That’s why the eclipse master Fred Espenak recommends using a telescope with a magnification of 50 to 100 times for witnessing the event.

Unless you are well-versed with the telescope and how to properly use solar filters, we advise you to seek out a public program via a nearby observatory or astronomy club. Never look at the sun through a telescope.

Click here to find a public presentation of the Mercury transit near you.

Or try an online view of the transit. The Virtual Telescope Project is hosting one.

View larger. | Want to watch online? The Virtual Telescope Project’s free online viewing session is scheduled for November 11, 2019, starting at 12:30 UTC (7:30 a.m. EST; translate UTC to your time). To join, and for more information, go to the Virtual Telescope Project website.

View larger. | The entire November 11, 2019, transit is visible from South America, eastern North America, and far-western Africa. Image via Eclipsewise.

What part of Earth will see the November 11 transit of Mercury? As shown on the worldwide chart above, the transit will be visible (at least in part) from most of the globe, with the exception of the shaded-out portion (Indonesia, most of Asia, and Australia). Mercury takes some 5 1/2 hours to cross the sun’s disk, and this transit of Mercury is entirely visible (given clear skies) from eastern North America, South America, the southern tip of Greenland, and far-western Africa.

For North America, the transit begins in the early morning hours on November 11. The eastern part of North America sees the start of the transit after sunrise November 11, whereas the western part sees the transit already in progress as the sun rises on November 11.

As for the world’s Eastern Hemisphere – Africa, Europe, the Middle East and New Zealand – the transit starts in the early afternoon November 11 in the westernmost parts of Africa and Europe, and in the late afternoon November 11 in eastern Europe and the Middle East. In New Zealand, the transit begins in the late afternoon on November 12.

We provide the geocentric (Earth-centered) contact times of the transit of Mercury in Universal Time (UTC). If you know how to convert Universal Time to your local time (here’s how to do it), you can get a good approximation of the contact times for the Mercury transit for your part of the world. NOTE: Because the transit is viewed from the Earth’s surface, instead of the Earth’s center, the contact times could differ from the geocentric contact times by up to a minute.

Read more: How to safely observe the Mercury transit

Transit of Mercury on 11 November 2019, from Society for Popular Astronomy on Vimeo.

View larger. | The transit times in Universal Time as viewed from the center of the Earth. Visit timeanddate.com to find out the local transit times from your part of the world. Image via EclipseWise.

November 11 transit times in Universal Time

First contact (ingress, exterior): 12:35:27 UT
Second contact (ingress, interior): 12:37:08 UT
Greatest transit: 15:19:48 UT
Third contact (egress, interior): 18:02:33 UT
Fourth contact (egress, exterior): 18:04:14 UT

Want to know if and when the transit happens in your sky? Click here to find out your local transit times via timeanddate.com.

Mercury transit times for select North American cities in your local time

The times below are in your local time (meaning no conversion is necessary). We give transit contact times for various North American cities and Honolulu, Hawaii.

NOTE: All places within the same time zone have very similar contact times.

Newfoundland Daylight Time (NST)

St. Johns, Newfoundland:
First contact (ingress, exterior): 9:05:56 a.m. NST
Second contact (ingress, interior): 9:07:38 a.m. NST
Greatest transit: 11:50:03 a.m. NST
Third contact (egress, interior): 2:32:33 p.m. NST
Fourth contact (egress, exterior): 2:34:14 p.m. NST

Atlantic Standard Time (AST)

Halifax, Nova Scotia:
First contact (ingress, exterior): 8:36:00 a.m. AST
Second contact (ingress, interior): 8:37:42 a.m. AST
Greatest transit: 11:20:08 a.m. AST
Third contact (egress, interior): 2:02:36 p.m. AST
Fourth contact (egress, exterior): 2:04:17 p.m. AST

Eastern Standard Time (EST)

New York City, New York:
First contact (ingress, exterior): 7:36:04 a.m. EST
Second contact (ingress, interior): 7:37:48 a.m. EST
Greatest transit: 10:20:13 a.m. EST
Third contact (egress, interior): 1:02:39 p.m. EST
Fourth contact (egress, exterior): 1:04:20 p.m. EST

Central Standard Time (CST)

New Orleans, Lousiana:
First contact (ingress, exterior): 6:36:08 a.m. CST
Second contact (ingress, interior): 6:37:49 a.m. CST
Greatest transit: 9:20:20 a.m. CST
Third contact (egress, interior): 12:02:45 p.m. CST
Fourth contact (egress, exterior): 12:04:26 p.m. CST

Mountain Standard Time (MST)

Denver, Colorado:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 8:20:24 a.m. MST
Third contact (egress, interior): 11:02:54 a.m. MST
Fourth contact (egress, exterior): 11:04:35 a.m. MST

Pacific Standard Time (PST)

Los Angeles, California:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 7:20:08 a.m. PST
Third contact (egress, interior): 10:03:00 a.m. PST
Fourth contact (egress, exterior): 10:04:41 a.m. PST

Alaska Standard Time (AKST)

Juneau, Alaska:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 7:40:25 a.m. AKST
Third contact (egress, interior): 9:03:04 a.m. AKST
Fourth contact (egress, exterior): 9:04:45 a.m. AKST

Hawaii-Aleutian Standard Time HST)

Honolulu, Hawaii:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: sun below horizon
Third contact (egress, interior): 8:03:13 a.m. HST
Fourth contact (egress, exterior): 8:04:54 a.m. HST

Transit contact times for many more North American cities via Fred Espenak’s EclipseWise.com:

United States Cities

Canadian Cities

Need more? More world transit times from timeanddate.com

May 9, 2016, transit of Mercury from Vegastar Carpentier Liard in France.

How common are transits of Mercury? Although much more common than transits of Venus, a transit of Mercury happens only 14 times in the 21st century (2001 to 2100).

Transits of Mercury always occur in either May or November.

The last four were in 1999 (November 15), 2003 (May 7), 2006 (November 8) and 2016 (May 9); the next will be on November 11, 2019, and the next after that will be November 13, 2032.

A planet that orbits the sun inside Earth’s orbit is called an inferior planet. When an inferior planet passes between the Earth and sun at inferior conjunction, it can pass north of the sun, south of the sun – or, in rare cases, right in front of the sun.

What causes a transit of Mercury? Only planets that orbit the sun inside of Earth’s orbit – Mercury and Venus – ever transit the sun, as seen from Earth. If Mercury orbited the sun on the same plane that Earth does, there would be three to four transits of Mercury each calendar year.

However, Mercury’s orbital plane in inclined at 7 degrees to the ecliptic (Earth’s orbital plane). That means when Mercury swings between the Earth and sun at inferior conjunction (see illustration below) every four or so months, Mercury usually sweeps to the north or south of the solar disk. Therefore a transit of Mercury is fairly rare, only happening 13 to 14 times per century.

Each time Mercury circles the sun in its short and swift orbit of 88 Earth-days, Mercury travels north of the ecliptic (Earth’s orbital plane) for about half its orbit, and south of the ecliptic during the other half of its orbit. Twice in its orbit, Mercury crosses the Earth’s orbital plane at points called nodes. When Mercury is traveling from north to south, it’s called a descending node; and when Mercury is traveling south to north, it’s called an ascending node.

Whenever Mercury crosses a node in close vicinity to reaching inferior conjunction, a transit of Mercury is not only possible but inevitable. Mercury crosses its ascending node almost concurrently with Mercury at inferior conjunction on November 11, 2019, to present a rather rare transit of Mercury.

Descending node transits can only happen during the first half of May, and ascending node transits in the first half of November. At other times of the year, Mercury at inferior conjunction would either pass north or south of the sun’s disk.

Bird’s-eye view of the inner solar system (Mercury, Venus, Earth and Mars) as seen from the north side of the ecliptic (Earth’s orbital plane) on November 11, 2019. From this vantage point, all the planets orbit the sun counterclockwise. The blue parts of the planetary orbits are north of the ecliptic plane whereas the green parts are south of the ecliptic. On November 11, 2019, Mercury crosses its ascending node, going from south to north, at nearly the same time that it passes between the Earth and sun at inferior conjunction Image via Solar System Live.

Dates for transits of Mercury in the 21st century (2001 to 2100). All Mercury transits happen in either May (descending node) or November (ascending node).

May 7, 2003
Nov 8, 2006
May 9, 2016
Nov 11, 2019
Nov 13, 2032
Nov 7, 2039
May 7, 2049
Nov 9, 2052
May 10, 2062
Nov 11, 2065
Nov 14, 2078
Nov 7, 2085
May 8, 2095
Nov 10, 2098

November (ascending node) transits happen about twice as often as May (descending node) transits. This is because Mercury has a very eccentric (oblong) orbit whereby Mercury comes a whopping 24 million kilometers (15 million miles) closer to the sun at perihelion (closest point to the sun in its orbit) than at aphelion (farthest point). In May, Mercury is rather close to aphelion, and quite far from the sun, which severely narrows the window of opportunity for a May transit. In November, Mercury swings rather near perihelion, and quite close to the sun, widening the period of time during which a November transit is possible.

Mercury transit cycles. Note that after a May transit, a November transit faithfully comes 3.5 years later (for instance: May 9, 2016 and November 11, 2019). Transits recur on nearly the same date in cycles of 46 years (for instance: May 9, 2016 and May 10, 2062). November transits, which are more common than May transits, occasionally recur in periods of 7 years, and more frequently in periods of 13 and 33 years.

May transits, which are less common than November transits, frequently recur in periods of 13 and/or 33 years. The 46-year cycle represents a combination of 13 and 33 years (13 + 33 = 46).

Seven century catalog of Mercury transits: 1601 A.D. to 2300 A.D.

May 9, 2016, Mercury transit as captured by Abhijit Juvekar in India. He wrote: “Although it is rare event to be seen from Earth, such transit events can be seen commonly any time if you have spaceship capable of going at exact place where you can see planet aligned with sun. Maybe in the future, people will see transit events like these while their routine trips from one planet to another just the same as we take train to commute from home to office today.” See more photos of the 2016 Mercury transit.

Bottom line: Our solar system’s innermost planet, Mercury, passes directly in front of the sun on November 11, 2019. Who will see it, how to watch, equipment needed, transit times.

from EarthSky https://ift.tt/2qD8nbD

Photo at top: Mercury transit, May 9, 2016 via @altair_astro on Twitter. See more photos of the 2016 Mercury transit.

Mercury – the innermost planet of our solar system – will transit the sun on November 11, 2019. In other words, Mercury will pass directly in front of the sun and be visible through telescopes with solar filters as a small black dot crossing the sun’s face. It’ll be visible in part from most of Earth’s globe. The entire transit is visible from South America, eastern North America, and far-western Africa.

The last transit of Mercury was in 2016. The next one won’t be until 2032.

Mercury will come into view on the sun’s face around 7:36 a.m. Eastern Standard Time (12:36 UTC; translate UTC to your time) on November 11. It’ll make a leisurely journey across the sun’s face, reaching greatest transit (closest to sun’s center) at approximately 10:20 a.m. EST (15:20 UTC) and finally exiting around 1:04 p.m. EST (18:04 UTC). The entire 5 1/2 hour path across the sun will be visible across the U.S. East – with magnification and proper solar filters – while those in the U.S. West can observe the transit already in progress after sunrise.

Translate UTC to your time

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

You need a telescope and solar filters to view the transit. Mercury’s diameter is only 1/194th of that of the sun, as seen from Earth. That’s why the eclipse master Fred Espenak recommends using a telescope with a magnification of 50 to 100 times for witnessing the event.

Unless you are well-versed with the telescope and how to properly use solar filters, we advise you to seek out a public program via a nearby observatory or astronomy club. Never look at the sun through a telescope.

Click here to find a public presentation of the Mercury transit near you.

Or try an online view of the transit. The Virtual Telescope Project is hosting one.

View larger. | Want to watch online? The Virtual Telescope Project’s free online viewing session is scheduled for November 11, 2019, starting at 12:30 UTC (7:30 a.m. EST; translate UTC to your time). To join, and for more information, go to the Virtual Telescope Project website.

View larger. | The entire November 11, 2019, transit is visible from South America, eastern North America, and far-western Africa. Image via Eclipsewise.

What part of Earth will see the November 11 transit of Mercury? As shown on the worldwide chart above, the transit will be visible (at least in part) from most of the globe, with the exception of the shaded-out portion (Indonesia, most of Asia, and Australia). Mercury takes some 5 1/2 hours to cross the sun’s disk, and this transit of Mercury is entirely visible (given clear skies) from eastern North America, South America, the southern tip of Greenland, and far-western Africa.

For North America, the transit begins in the early morning hours on November 11. The eastern part of North America sees the start of the transit after sunrise November 11, whereas the western part sees the transit already in progress as the sun rises on November 11.

As for the world’s Eastern Hemisphere – Africa, Europe, the Middle East and New Zealand – the transit starts in the early afternoon November 11 in the westernmost parts of Africa and Europe, and in the late afternoon November 11 in eastern Europe and the Middle East. In New Zealand, the transit begins in the late afternoon on November 12.

We provide the geocentric (Earth-centered) contact times of the transit of Mercury in Universal Time (UTC). If you know how to convert Universal Time to your local time (here’s how to do it), you can get a good approximation of the contact times for the Mercury transit for your part of the world. NOTE: Because the transit is viewed from the Earth’s surface, instead of the Earth’s center, the contact times could differ from the geocentric contact times by up to a minute.

Read more: How to safely observe the Mercury transit

Transit of Mercury on 11 November 2019, from Society for Popular Astronomy on Vimeo.

View larger. | The transit times in Universal Time as viewed from the center of the Earth. Visit timeanddate.com to find out the local transit times from your part of the world. Image via EclipseWise.

November 11 transit times in Universal Time

First contact (ingress, exterior): 12:35:27 UT
Second contact (ingress, interior): 12:37:08 UT
Greatest transit: 15:19:48 UT
Third contact (egress, interior): 18:02:33 UT
Fourth contact (egress, exterior): 18:04:14 UT

Want to know if and when the transit happens in your sky? Click here to find out your local transit times via timeanddate.com.

Mercury transit times for select North American cities in your local time

The times below are in your local time (meaning no conversion is necessary). We give transit contact times for various North American cities and Honolulu, Hawaii.

NOTE: All places within the same time zone have very similar contact times.

Newfoundland Daylight Time (NST)

St. Johns, Newfoundland:
First contact (ingress, exterior): 9:05:56 a.m. NST
Second contact (ingress, interior): 9:07:38 a.m. NST
Greatest transit: 11:50:03 a.m. NST
Third contact (egress, interior): 2:32:33 p.m. NST
Fourth contact (egress, exterior): 2:34:14 p.m. NST

Atlantic Standard Time (AST)

Halifax, Nova Scotia:
First contact (ingress, exterior): 8:36:00 a.m. AST
Second contact (ingress, interior): 8:37:42 a.m. AST
Greatest transit: 11:20:08 a.m. AST
Third contact (egress, interior): 2:02:36 p.m. AST
Fourth contact (egress, exterior): 2:04:17 p.m. AST

Eastern Standard Time (EST)

New York City, New York:
First contact (ingress, exterior): 7:36:04 a.m. EST
Second contact (ingress, interior): 7:37:48 a.m. EST
Greatest transit: 10:20:13 a.m. EST
Third contact (egress, interior): 1:02:39 p.m. EST
Fourth contact (egress, exterior): 1:04:20 p.m. EST

Central Standard Time (CST)

New Orleans, Lousiana:
First contact (ingress, exterior): 6:36:08 a.m. CST
Second contact (ingress, interior): 6:37:49 a.m. CST
Greatest transit: 9:20:20 a.m. CST
Third contact (egress, interior): 12:02:45 p.m. CST
Fourth contact (egress, exterior): 12:04:26 p.m. CST

Mountain Standard Time (MST)

Denver, Colorado:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 8:20:24 a.m. MST
Third contact (egress, interior): 11:02:54 a.m. MST
Fourth contact (egress, exterior): 11:04:35 a.m. MST

Pacific Standard Time (PST)

Los Angeles, California:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 7:20:08 a.m. PST
Third contact (egress, interior): 10:03:00 a.m. PST
Fourth contact (egress, exterior): 10:04:41 a.m. PST

Alaska Standard Time (AKST)

Juneau, Alaska:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: 7:40:25 a.m. AKST
Third contact (egress, interior): 9:03:04 a.m. AKST
Fourth contact (egress, exterior): 9:04:45 a.m. AKST

Hawaii-Aleutian Standard Time HST)

Honolulu, Hawaii:
First contact (ingress, exterior): sun below horizon
Second contact (ingress, interior): sun below horizon
Greatest transit: sun below horizon
Third contact (egress, interior): 8:03:13 a.m. HST
Fourth contact (egress, exterior): 8:04:54 a.m. HST

Transit contact times for many more North American cities via Fred Espenak’s EclipseWise.com:

United States Cities

Canadian Cities

Need more? More world transit times from timeanddate.com

May 9, 2016, transit of Mercury from Vegastar Carpentier Liard in France.

How common are transits of Mercury? Although much more common than transits of Venus, a transit of Mercury happens only 14 times in the 21st century (2001 to 2100).

Transits of Mercury always occur in either May or November.

The last four were in 1999 (November 15), 2003 (May 7), 2006 (November 8) and 2016 (May 9); the next will be on November 11, 2019, and the next after that will be November 13, 2032.

A planet that orbits the sun inside Earth’s orbit is called an inferior planet. When an inferior planet passes between the Earth and sun at inferior conjunction, it can pass north of the sun, south of the sun – or, in rare cases, right in front of the sun.

What causes a transit of Mercury? Only planets that orbit the sun inside of Earth’s orbit – Mercury and Venus – ever transit the sun, as seen from Earth. If Mercury orbited the sun on the same plane that Earth does, there would be three to four transits of Mercury each calendar year.

However, Mercury’s orbital plane in inclined at 7 degrees to the ecliptic (Earth’s orbital plane). That means when Mercury swings between the Earth and sun at inferior conjunction (see illustration below) every four or so months, Mercury usually sweeps to the north or south of the solar disk. Therefore a transit of Mercury is fairly rare, only happening 13 to 14 times per century.

Each time Mercury circles the sun in its short and swift orbit of 88 Earth-days, Mercury travels north of the ecliptic (Earth’s orbital plane) for about half its orbit, and south of the ecliptic during the other half of its orbit. Twice in its orbit, Mercury crosses the Earth’s orbital plane at points called nodes. When Mercury is traveling from north to south, it’s called a descending node; and when Mercury is traveling south to north, it’s called an ascending node.

Whenever Mercury crosses a node in close vicinity to reaching inferior conjunction, a transit of Mercury is not only possible but inevitable. Mercury crosses its ascending node almost concurrently with Mercury at inferior conjunction on November 11, 2019, to present a rather rare transit of Mercury.

Descending node transits can only happen during the first half of May, and ascending node transits in the first half of November. At other times of the year, Mercury at inferior conjunction would either pass north or south of the sun’s disk.

Bird’s-eye view of the inner solar system (Mercury, Venus, Earth and Mars) as seen from the north side of the ecliptic (Earth’s orbital plane) on November 11, 2019. From this vantage point, all the planets orbit the sun counterclockwise. The blue parts of the planetary orbits are north of the ecliptic plane whereas the green parts are south of the ecliptic. On November 11, 2019, Mercury crosses its ascending node, going from south to north, at nearly the same time that it passes between the Earth and sun at inferior conjunction Image via Solar System Live.

Dates for transits of Mercury in the 21st century (2001 to 2100). All Mercury transits happen in either May (descending node) or November (ascending node).

May 7, 2003
Nov 8, 2006
May 9, 2016
Nov 11, 2019
Nov 13, 2032
Nov 7, 2039
May 7, 2049
Nov 9, 2052
May 10, 2062
Nov 11, 2065
Nov 14, 2078
Nov 7, 2085
May 8, 2095
Nov 10, 2098

November (ascending node) transits happen about twice as often as May (descending node) transits. This is because Mercury has a very eccentric (oblong) orbit whereby Mercury comes a whopping 24 million kilometers (15 million miles) closer to the sun at perihelion (closest point to the sun in its orbit) than at aphelion (farthest point). In May, Mercury is rather close to aphelion, and quite far from the sun, which severely narrows the window of opportunity for a May transit. In November, Mercury swings rather near perihelion, and quite close to the sun, widening the period of time during which a November transit is possible.

Mercury transit cycles. Note that after a May transit, a November transit faithfully comes 3.5 years later (for instance: May 9, 2016 and November 11, 2019). Transits recur on nearly the same date in cycles of 46 years (for instance: May 9, 2016 and May 10, 2062). November transits, which are more common than May transits, occasionally recur in periods of 7 years, and more frequently in periods of 13 and 33 years.

May transits, which are less common than November transits, frequently recur in periods of 13 and/or 33 years. The 46-year cycle represents a combination of 13 and 33 years (13 + 33 = 46).

Seven century catalog of Mercury transits: 1601 A.D. to 2300 A.D.

May 9, 2016, Mercury transit as captured by Abhijit Juvekar in India. He wrote: “Although it is rare event to be seen from Earth, such transit events can be seen commonly any time if you have spaceship capable of going at exact place where you can see planet aligned with sun. Maybe in the future, people will see transit events like these while their routine trips from one planet to another just the same as we take train to commute from home to office today.” See more photos of the 2016 Mercury transit.

Bottom line: Our solar system’s innermost planet, Mercury, passes directly in front of the sun on November 11, 2019. Who will see it, how to watch, equipment needed, transit times.

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Is Hygiea now the smallest dwarf planet?

This is the best view yet of asteroid Hygiea in the main asteroid belt, from ESO’s Very Large Telescope (VLT). Hygiea is now seen to be nearly spherical, meaning it could possibly be classified as a dwarf planet. Image via ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS).

The dwarf planets in our solar system are intriguing worlds, not large enough to be full-fledged planets, yet still distinct from asteroids. Eris and Pluto are the largest known of our solar system’s dwarf planets, and Ceres is the smallest of the current five official dwarf planets. But now there is a new contender for smallest dwarf planet: Hygiea.

Hygiea is the fourth largest object in the main asteroid belt between Mars and Jupiter, after Ceres (which is also counted as an asteroid), Vesta and Pallas. However, new observations from the European Southern Observatory’s (ESO) Very Large Telescope (VLT) – using the SPHERE instrument – suggest that it should be classified as a dwarf planet. The new peer-reviewed results were published on October 28, 2019, in Nature Astronomy. SPHERE is used primarily for taking images of larger exoplanets around other stars.

Hygiea was already known to have three of the four characteristics of dwarf planets: it orbits the sun, is not a moon and has not cleared its orbit of other rocky debris. But the fourth requirement was still unknown: its shape. Was it massive enough to be roughly spherical? If so, then it would fulfill all the criteria to be considered a dwarf planet.

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Comparison of the five currently classified dwarf planets with the moon. Could Hygiea now be the sixth largest (and smallest) dwarf planet? Image via Karl Tate/SPACE.com.

Now, thanks to VLT, we finally know the shape of Hygiea, and it is nearly spherical. According to Pierre Vernazza from the Laboratoire d’Astrophysique de Marseille in France:

Thanks to the unique capability of the SPHERE instrument on the VLT, which is one of the most powerful imaging systems in the world, we could resolve Hygiea’s shape, which turns out to be nearly spherical. Thanks to these images, Hygiea may be reclassified as a dwarf planet, so far the smallest in the solar system.

Not only was VLT able to see Hygiea’s shape for the first time, it also provided better measurements as to its size, which turns out to be just over 267 miles (430 km). That would make it the sixth largest (and smallest) dwarf planet, smaller than Ceres, which is about 592 miles (952 km) in size.

Whether Hygiea actually will be classified as a dwarf planet remains to be seen, but there certainly seems to be a good case now for doing so.

The new observations also revealed another surprise: no sign of the very large impact crater that had been expected. Since Hygiea is part of one of the main asteroid families in the asteroid belt – nearly 7,000 objects all originating from the same parent body – scientists thought it would have a large, deep collision mark, but it didn’t. Vernazza said:

This result came as a real surprise as we were expecting the presence of a large impact basin, as is the case on Vesta.

About 95% of Hygiea’s surface was visible during the observations, but no massive impact crater was seen, only two smaller craters. As study co-author Miroslav Brož of the Astronomical Institute of Charles University in Prague, Czech Republic, explained:

Neither of these two craters could have been caused by the impact that originated the Hygiea family of asteroids whose volume is comparable to that of a 100 km-sized object. They are too small.

The researchers decided to investigate further. They concluded that both Hygiea’s shape and the large family of asteroids it is part of, are the result of a major collision with a large rocky object, between 75 and 150 km diameter, with the former parent body, about 2 billion years ago. According to Pavel Sevecek, a Ph.D. student at the Astronomical Institute of Charles University:

Such a collision between two large bodies in the asteroid belt is unique in the last 3-4 billion years.

Size comparison of asteroids Hygiea, Vesta and Ceres. Ceres is also classified as a dwarf planet. Image via ESO/P. Vernazza et al., L. Jorda et al./MISTRAL algorithm (ONERA/CNRS).

From the abstract:

Numerical simulations of the family forming event show that Hygiea’s spherical shape and family can be explained by a collision with a large projectile (Diameter~75-150 km). By comparing Hygiea’s sphericity with that of other solar system objects, it appears that Hygiea is nearly as spherical as Ceres, opening a possibility for this object to be reclassified as a dwarf planet.

Thanks to advances like VLT’s SPHERE instrument, scientists are now getting better views of main belt asteroids in general, apart from just Hygiea, as Vernazza noted:

Thanks to the VLT and the new generation adaptive-optics instrument SPHERE, we are now imaging main belt asteroids with unprecedented resolution, closing the gap between Earth-based and interplanetary mission observations.

In previous views of Hygiea, the object just looked like a very bright star. Image via 2MASS Survey/Wikipedia.

If Hygiea is classified as a dwarf planet – which will now likely face some debate – it will join a small but fascinating group of objects that are more evolved than asteroids but didn’t quite make the cut for full planethood.

Bottom line: Astronomers have found that Hygiea, an asteroid in the main asteroid belt, is round, which may mean it now can be classified as the smallest-known dwarf planet in the solar system.

Source: A basin-free spherical shape as outcome of a giant impact on asteroid Hygiea

Via ESO

from EarthSky https://ift.tt/2NtMDs4

This is the best view yet of asteroid Hygiea in the main asteroid belt, from ESO’s Very Large Telescope (VLT). Hygiea is now seen to be nearly spherical, meaning it could possibly be classified as a dwarf planet. Image via ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS).

The dwarf planets in our solar system are intriguing worlds, not large enough to be full-fledged planets, yet still distinct from asteroids. Eris and Pluto are the largest known of our solar system’s dwarf planets, and Ceres is the smallest of the current five official dwarf planets. But now there is a new contender for smallest dwarf planet: Hygiea.

Hygiea is the fourth largest object in the main asteroid belt between Mars and Jupiter, after Ceres (which is also counted as an asteroid), Vesta and Pallas. However, new observations from the European Southern Observatory’s (ESO) Very Large Telescope (VLT) – using the SPHERE instrument – suggest that it should be classified as a dwarf planet. The new peer-reviewed results were published on October 28, 2019, in Nature Astronomy. SPHERE is used primarily for taking images of larger exoplanets around other stars.

Hygiea was already known to have three of the four characteristics of dwarf planets: it orbits the sun, is not a moon and has not cleared its orbit of other rocky debris. But the fourth requirement was still unknown: its shape. Was it massive enough to be roughly spherical? If so, then it would fulfill all the criteria to be considered a dwarf planet.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Comparison of the five currently classified dwarf planets with the moon. Could Hygiea now be the sixth largest (and smallest) dwarf planet? Image via Karl Tate/SPACE.com.

Now, thanks to VLT, we finally know the shape of Hygiea, and it is nearly spherical. According to Pierre Vernazza from the Laboratoire d’Astrophysique de Marseille in France:

Thanks to the unique capability of the SPHERE instrument on the VLT, which is one of the most powerful imaging systems in the world, we could resolve Hygiea’s shape, which turns out to be nearly spherical. Thanks to these images, Hygiea may be reclassified as a dwarf planet, so far the smallest in the solar system.

Not only was VLT able to see Hygiea’s shape for the first time, it also provided better measurements as to its size, which turns out to be just over 267 miles (430 km). That would make it the sixth largest (and smallest) dwarf planet, smaller than Ceres, which is about 592 miles (952 km) in size.

Whether Hygiea actually will be classified as a dwarf planet remains to be seen, but there certainly seems to be a good case now for doing so.

The new observations also revealed another surprise: no sign of the very large impact crater that had been expected. Since Hygiea is part of one of the main asteroid families in the asteroid belt – nearly 7,000 objects all originating from the same parent body – scientists thought it would have a large, deep collision mark, but it didn’t. Vernazza said:

This result came as a real surprise as we were expecting the presence of a large impact basin, as is the case on Vesta.

About 95% of Hygiea’s surface was visible during the observations, but no massive impact crater was seen, only two smaller craters. As study co-author Miroslav Brož of the Astronomical Institute of Charles University in Prague, Czech Republic, explained:

Neither of these two craters could have been caused by the impact that originated the Hygiea family of asteroids whose volume is comparable to that of a 100 km-sized object. They are too small.

The researchers decided to investigate further. They concluded that both Hygiea’s shape and the large family of asteroids it is part of, are the result of a major collision with a large rocky object, between 75 and 150 km diameter, with the former parent body, about 2 billion years ago. According to Pavel Sevecek, a Ph.D. student at the Astronomical Institute of Charles University:

Such a collision between two large bodies in the asteroid belt is unique in the last 3-4 billion years.

Size comparison of asteroids Hygiea, Vesta and Ceres. Ceres is also classified as a dwarf planet. Image via ESO/P. Vernazza et al., L. Jorda et al./MISTRAL algorithm (ONERA/CNRS).

From the abstract:

Numerical simulations of the family forming event show that Hygiea’s spherical shape and family can be explained by a collision with a large projectile (Diameter~75-150 km). By comparing Hygiea’s sphericity with that of other solar system objects, it appears that Hygiea is nearly as spherical as Ceres, opening a possibility for this object to be reclassified as a dwarf planet.

Thanks to advances like VLT’s SPHERE instrument, scientists are now getting better views of main belt asteroids in general, apart from just Hygiea, as Vernazza noted:

Thanks to the VLT and the new generation adaptive-optics instrument SPHERE, we are now imaging main belt asteroids with unprecedented resolution, closing the gap between Earth-based and interplanetary mission observations.

In previous views of Hygiea, the object just looked like a very bright star. Image via 2MASS Survey/Wikipedia.

If Hygiea is classified as a dwarf planet – which will now likely face some debate – it will join a small but fascinating group of objects that are more evolved than asteroids but didn’t quite make the cut for full planethood.

Bottom line: Astronomers have found that Hygiea, an asteroid in the main asteroid belt, is round, which may mean it now can be classified as the smallest-known dwarf planet in the solar system.

Source: A basin-free spherical shape as outcome of a giant impact on asteroid Hygiea

Via ESO

from EarthSky https://ift.tt/2NtMDs4

Edmond Halley’s magnificent prediction

Comet Halley, photographed in 1986, via NASA.

November 8, 1656. English astronomer and mathematician Edmond Halley was born on this date near London. He became the first to calculate the orbit of a comet, arguably the most famous of all comets today, named Comet Halley in his honor. He was also friends with Isaac Newton and contributed to Newton’s development of the theory of gravity, which helped establish our modern era of science, in part by removing all doubt that we live on a planet orbiting around a sun.

When Comet Halley last appeared in Earth’s skies, in 1986, it was met in space by an international fleet of spacecraft. This famous comet will return again in 2061 on its 76-year journey around the sun. It’s famous in part because it tends to be a bright comet in Earth’s skies; at the 1986 return, many people saw it. Also, because of the length of the comet’s orbit – 76 years – many on Earth will see again.

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Portrait of Edmond Halley circa 1687 by Thomas Murray via Wikimedia Commons.

But, in Edmond Halley’s time, people didn’t know that comets were like planets in being bound in orbit by the sun. They didn’t know that some comet, like Comet Halley, return over and over. Comets were thought to pass only once through our solar system. In the year 1704, Halley had become a professor of Geometry at Oxford. The following year, he published A Synopsis of the Astronomy of Comets. The book contains the parabolic orbits of 24 comets observed from 1337 to 1698.

It’s also in this book that Halley remarks on three comets that appeared in 1531, 1607, and 1682. He used Isaac Newton’s theories of gravitation and planetary motions to compute the orbits of these comets, finding remarkable similarities in their orbits. Then Halley made a leap and made what was, at that time, a stunning prediction. He said these three comets must in fact be a single comet, which returns periodically every 76 years.

He then predicted the comet would return, saying:

Hence I dare venture to foretell, that it will return again in the year 1758.

Halley didn’t live to see his prediction verified. It was 16 years after his death that – right on schedule, in 1758 – the comet did return. The scientific world – and the public – were stunned.

It was the first comet ever predicted to return. It’s now called Comet Halley, in honor of Edmond Halley.

At the last return of Comet Halley – in 1986 – the European spacecraft Giotto became one of the first spacecraft ever to encounter and photograph a comet’s nucleus, or core. It swept past the nucleus of Comet Halley as the comet receded from the sun. Image via Halley Multicolor Camera Team/Giotto Project/ESA/NASA.

The 17th century was an exciting time to be a scientist in England. The scientific revolution gave birth to the Royal Society of London when Halley was only a child. Members of the Royal Society – physicians and natural philosophers who were some of the earliest adopters of the scientific method – met weekly. The first Astronomer Royal was John Flamsteed, who is remembered in part for the creation of the Royal Observatory at Greenwich, which still exists today.

After entering Queen’s College in Oxford in 1673, Halley was introduced to Flamsteed. Halley had the chance to visit him in his observatory on a few occasions during which Flamsteed encouraged him to pursue astronomy.

At that time, Flamsteed’s project was to assemble an accurate catalog of the northern stars with his telescope. Halley thought he would do the same, but with stars of the Southern Hemisphere.

His journey southward began in November 1676, even before he obtained his university degree. He sailed aboard a ship from the East India Company to the island of St. Helena, still one of the most remote islands in the world and the southernmost territory occupied by the British. His father and King Charles II financed the trip.

In spite of bad weather that made Halley’s work difficult, when he turned to sail back home in January 1678, he brought records of the longitude and latitude of 341 stars and many other observations including a transit of Mercury. Of the transit, he wrote:

This sight … is by far the noblest astronomy affords.

Here’s the last transit of Mercury – May 9, 2016 – via Vegastar Carpentier Liard of France. In this image, Mercury is the small black dot on the left side the sun. There’s another Mercury transit coming up on November 11, 2019. Read more about the coming Mercury transit.

Halley’s catalog of southern stars was published by the end of 1678, and – as the first work of its genre – it was a huge success. No one had ever attempted to determine the locations of southern stars with a telescope before. The catalog was Halley’s glorious debut as an astronomer. In the same year, he received his M.A from the University of Oxford and was elected a fellow of the Royal Society.

Halley visited Isaac Newton in Cambridge for the first time in 1684. A group of Royal Society members including physicist and biologist Robert Hooke, architect Christopher Wren and Isaac Newton were trying to crack the code of planetary motion. Halley was the youngest to join the trio in their mission to use mathematics to describe how – and why – the planets move around the sun. They were all competing against one another to find the solution first, which was very motivating. Their problem was to find a mechanical model that would keep the planet orbiting around the sun without it escaping the orbit or falling into the star.

Hooke and Halley determined that the solution to this problem would be a force that keeps a planet in orbit around a star and must decrease as the inverse square of its distance from the star, what we today know as the inverse-square law.

Hooke and Halley were on the right track, but they were not able to create a theoretical orbit that would match observations, in spite of a monetary prize to be given by Wren.

Halley visited Newton and explained the concept to him, also explaining that he couldn’t prove it. Newton, encouraged by Halley, developed Halley’s work into one of the most famous scientific works to this day, Mathematical Principles of Natural Philosophy, often referred to simply as Newton’s Principia.

Copy of the third edition of the Principia (1726) at the John Reynolds Library in Manchester, England. Via Wikimedia Commons.

Halley is also known for his work in meteorology. He put his talent of giving meaning to great amounts of data to use by creating a map of the world in 1686.

The map showed the most important winds above the oceans. It is considered as the first meteorological chart to be published.

Edmond Halley’s 1686 map of the world, which charts the directions of trade winds and monsoons and is considered the 1st meteorological map. Via princeton.edu.

Halley kept travelling and working on many other projects, such as attempting to link mortality and age in a population. This data was later used by actuaries for life insurance.

In 1720, Halley succeeded Flamsteed and became the second Astronomer Royal at Greenwich.

Bottom line: Astronomer Edmond Halley – for whom Halley’s Comet is named – was born on November 8, 1656.

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Comet Halley, photographed in 1986, via NASA.

November 8, 1656. English astronomer and mathematician Edmond Halley was born on this date near London. He became the first to calculate the orbit of a comet, arguably the most famous of all comets today, named Comet Halley in his honor. He was also friends with Isaac Newton and contributed to Newton’s development of the theory of gravity, which helped establish our modern era of science, in part by removing all doubt that we live on a planet orbiting around a sun.

When Comet Halley last appeared in Earth’s skies, in 1986, it was met in space by an international fleet of spacecraft. This famous comet will return again in 2061 on its 76-year journey around the sun. It’s famous in part because it tends to be a bright comet in Earth’s skies; at the 1986 return, many people saw it. Also, because of the length of the comet’s orbit – 76 years – many on Earth will see again.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

Portrait of Edmond Halley circa 1687 by Thomas Murray via Wikimedia Commons.

But, in Edmond Halley’s time, people didn’t know that comets were like planets in being bound in orbit by the sun. They didn’t know that some comet, like Comet Halley, return over and over. Comets were thought to pass only once through our solar system. In the year 1704, Halley had become a professor of Geometry at Oxford. The following year, he published A Synopsis of the Astronomy of Comets. The book contains the parabolic orbits of 24 comets observed from 1337 to 1698.

It’s also in this book that Halley remarks on three comets that appeared in 1531, 1607, and 1682. He used Isaac Newton’s theories of gravitation and planetary motions to compute the orbits of these comets, finding remarkable similarities in their orbits. Then Halley made a leap and made what was, at that time, a stunning prediction. He said these three comets must in fact be a single comet, which returns periodically every 76 years.

He then predicted the comet would return, saying:

Hence I dare venture to foretell, that it will return again in the year 1758.

Halley didn’t live to see his prediction verified. It was 16 years after his death that – right on schedule, in 1758 – the comet did return. The scientific world – and the public – were stunned.

It was the first comet ever predicted to return. It’s now called Comet Halley, in honor of Edmond Halley.

At the last return of Comet Halley – in 1986 – the European spacecraft Giotto became one of the first spacecraft ever to encounter and photograph a comet’s nucleus, or core. It swept past the nucleus of Comet Halley as the comet receded from the sun. Image via Halley Multicolor Camera Team/Giotto Project/ESA/NASA.

The 17th century was an exciting time to be a scientist in England. The scientific revolution gave birth to the Royal Society of London when Halley was only a child. Members of the Royal Society – physicians and natural philosophers who were some of the earliest adopters of the scientific method – met weekly. The first Astronomer Royal was John Flamsteed, who is remembered in part for the creation of the Royal Observatory at Greenwich, which still exists today.

After entering Queen’s College in Oxford in 1673, Halley was introduced to Flamsteed. Halley had the chance to visit him in his observatory on a few occasions during which Flamsteed encouraged him to pursue astronomy.

At that time, Flamsteed’s project was to assemble an accurate catalog of the northern stars with his telescope. Halley thought he would do the same, but with stars of the Southern Hemisphere.

His journey southward began in November 1676, even before he obtained his university degree. He sailed aboard a ship from the East India Company to the island of St. Helena, still one of the most remote islands in the world and the southernmost territory occupied by the British. His father and King Charles II financed the trip.

In spite of bad weather that made Halley’s work difficult, when he turned to sail back home in January 1678, he brought records of the longitude and latitude of 341 stars and many other observations including a transit of Mercury. Of the transit, he wrote:

This sight … is by far the noblest astronomy affords.

Here’s the last transit of Mercury – May 9, 2016 – via Vegastar Carpentier Liard of France. In this image, Mercury is the small black dot on the left side the sun. There’s another Mercury transit coming up on November 11, 2019. Read more about the coming Mercury transit.

Halley’s catalog of southern stars was published by the end of 1678, and – as the first work of its genre – it was a huge success. No one had ever attempted to determine the locations of southern stars with a telescope before. The catalog was Halley’s glorious debut as an astronomer. In the same year, he received his M.A from the University of Oxford and was elected a fellow of the Royal Society.

Halley visited Isaac Newton in Cambridge for the first time in 1684. A group of Royal Society members including physicist and biologist Robert Hooke, architect Christopher Wren and Isaac Newton were trying to crack the code of planetary motion. Halley was the youngest to join the trio in their mission to use mathematics to describe how – and why – the planets move around the sun. They were all competing against one another to find the solution first, which was very motivating. Their problem was to find a mechanical model that would keep the planet orbiting around the sun without it escaping the orbit or falling into the star.

Hooke and Halley determined that the solution to this problem would be a force that keeps a planet in orbit around a star and must decrease as the inverse square of its distance from the star, what we today know as the inverse-square law.

Hooke and Halley were on the right track, but they were not able to create a theoretical orbit that would match observations, in spite of a monetary prize to be given by Wren.

Halley visited Newton and explained the concept to him, also explaining that he couldn’t prove it. Newton, encouraged by Halley, developed Halley’s work into one of the most famous scientific works to this day, Mathematical Principles of Natural Philosophy, often referred to simply as Newton’s Principia.

Copy of the third edition of the Principia (1726) at the John Reynolds Library in Manchester, England. Via Wikimedia Commons.

Halley is also known for his work in meteorology. He put his talent of giving meaning to great amounts of data to use by creating a map of the world in 1686.

The map showed the most important winds above the oceans. It is considered as the first meteorological chart to be published.

Edmond Halley’s 1686 map of the world, which charts the directions of trade winds and monsoons and is considered the 1st meteorological map. Via princeton.edu.

Halley kept travelling and working on many other projects, such as attempting to link mortality and age in a population. This data was later used by actuaries for life insurance.

In 1720, Halley succeeded Flamsteed and became the second Astronomer Royal at Greenwich.

Bottom line: Astronomer Edmond Halley – for whom Halley’s Comet is named – was born on November 8, 1656.

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A deep look at Orion

View larger. | Image via Fred Espenak.

Perhaps you know the constellation Orion for its 3 prominent Belt stars, or its famous Orion Nebula, or its bright stars Betelgeuse and Rigel. Here’s a deeper look at this area of sky, revealing many of bright and faint nebulae. On November 4, 2019, our friend Fred Espenak – aka Mr. Eclipse – wrote:

I’ve been working on the processing of this image (on and off) for a week or so … The image is actually a composite of seven 4-minute exposures (F/4, ISO 1600) with a modified Nikon D750 and a Nikon 50mm f/1.8 lens.

Thanks for sharing your image with us, Fred!

Casual stargazers using the eye alone will start noticing and commenting on Orion around now. It’s visible by mid-evening and highest in the sky this month after midnight. By about January, Orion will be even more prominent and noticeable in the evening sky.

Bottom line: Deep-sky photo of the area around the constellation Orion, by Fred Espenak.

from EarthSky https://ift.tt/36NPlzZ

View larger. | Image via Fred Espenak.

Perhaps you know the constellation Orion for its 3 prominent Belt stars, or its famous Orion Nebula, or its bright stars Betelgeuse and Rigel. Here’s a deeper look at this area of sky, revealing many of bright and faint nebulae. On November 4, 2019, our friend Fred Espenak – aka Mr. Eclipse – wrote:

I’ve been working on the processing of this image (on and off) for a week or so … The image is actually a composite of seven 4-minute exposures (F/4, ISO 1600) with a modified Nikon D750 and a Nikon 50mm f/1.8 lens.

Thanks for sharing your image with us, Fred!

Casual stargazers using the eye alone will start noticing and commenting on Orion around now. It’s visible by mid-evening and highest in the sky this month after midnight. By about January, Orion will be even more prominent and noticeable in the evening sky.

Bottom line: Deep-sky photo of the area around the constellation Orion, by Fred Espenak.

from EarthSky https://ift.tt/36NPlzZ

Red Mars and blue-white Spica pair up in morning sky

In the eastern morning sky around November 8, 9 and 10, 2019 – as the predawn darkness gives way to dawn – watch for the red planet Mars to pair up with blue-white Spica, brightest star in the constellation Virgo the Maiden. Their conjunction date – when Mars passes three degrees north of Spica on our sky’s dome – is November 8.

These two worlds will remain close together all week long, and should rather easily fit into a single binocular field.

Spica – a 1st-magnitude star – shines about twice as brightly as Mars does right now. So, in the early morning, you might see Spica – but not Mars – with the eye alone. If that’s the case, aim binoculars at Spica to view nearby Mars and Spica adorning the same binocular field together. Note the beautiful contrast of color between blue-white Spica and ruddy Mars.

The Northern Hemisphere has the advantage for watching the early morning Mars/Spica spectacle. That’s because Mars and Spica rise earlier before sunrise at more northerly latitudes, and closer to sunrise at more southerly latitudes. Here are the approximate rising times for Mars at various latitudes (presuming an absolutely level horizon) for the next several days:

35 degrees north latitude
Mars rises 1 3/4 hours before sunrise

Equator (0 degrees latitude)
Mars rises 1 1/2 hours before sunrise

35 degrees south latitude
Mars rises 1 hour before sunrise

Want more specific rising times for your sky? Click here for an almanac.

The good news is that both Mars and Spica rise earlier in the morning sky with each successive day. But Spica climbs away from the sunrise at a greater clip than Mars does. So it won’t be too much longer before Mars falls beneath Spica in the November 2019 morning sky. And by the time the moon reaches this part of the sky on the mornings of November 23 and 24, 2019, Mars will be found roughly midway between Spica and the planet Mercury on the sky’s dome, as shown on the sky chart below.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

If you’re an early bird, waking up before the sun, then use the moon, and the star Spica to help you envision the ecliptic with the mind’s eye, and to find Mars and Mercury. Read more.

Mercury is nominally an evening “star” right now. Yet this world, named in honor of the fleet-footed messenger god, will transition from the evening to morning sky on November 11, 2019. Roughly a week thereafter, look for Mercury to take the stage with Mars and Spica in the morning sky.

Bottom line: These next several days – November 8, 9 and 10, 2019 – watch for the close pairing of the red planet Mars and the blue-white star Spica in the early morning sky.

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In the eastern morning sky around November 8, 9 and 10, 2019 – as the predawn darkness gives way to dawn – watch for the red planet Mars to pair up with blue-white Spica, brightest star in the constellation Virgo the Maiden. Their conjunction date – when Mars passes three degrees north of Spica on our sky’s dome – is November 8.

These two worlds will remain close together all week long, and should rather easily fit into a single binocular field.

Spica – a 1st-magnitude star – shines about twice as brightly as Mars does right now. So, in the early morning, you might see Spica – but not Mars – with the eye alone. If that’s the case, aim binoculars at Spica to view nearby Mars and Spica adorning the same binocular field together. Note the beautiful contrast of color between blue-white Spica and ruddy Mars.

The Northern Hemisphere has the advantage for watching the early morning Mars/Spica spectacle. That’s because Mars and Spica rise earlier before sunrise at more northerly latitudes, and closer to sunrise at more southerly latitudes. Here are the approximate rising times for Mars at various latitudes (presuming an absolutely level horizon) for the next several days:

35 degrees north latitude
Mars rises 1 3/4 hours before sunrise

Equator (0 degrees latitude)
Mars rises 1 1/2 hours before sunrise

35 degrees south latitude
Mars rises 1 hour before sunrise

Want more specific rising times for your sky? Click here for an almanac.

The good news is that both Mars and Spica rise earlier in the morning sky with each successive day. But Spica climbs away from the sunrise at a greater clip than Mars does. So it won’t be too much longer before Mars falls beneath Spica in the November 2019 morning sky. And by the time the moon reaches this part of the sky on the mornings of November 23 and 24, 2019, Mars will be found roughly midway between Spica and the planet Mercury on the sky’s dome, as shown on the sky chart below.

EarthSky 2020 lunar calendars are available! They make great gifts. Order now. Going fast!

If you’re an early bird, waking up before the sun, then use the moon, and the star Spica to help you envision the ecliptic with the mind’s eye, and to find Mars and Mercury. Read more.

Mercury is nominally an evening “star” right now. Yet this world, named in honor of the fleet-footed messenger god, will transition from the evening to morning sky on November 11, 2019. Roughly a week thereafter, look for Mercury to take the stage with Mars and Spica in the morning sky.

Bottom line: These next several days – November 8, 9 and 10, 2019 – watch for the close pairing of the red planet Mars and the blue-white star Spica in the early morning sky.

from EarthSky https://ift.tt/2PXq1Sa