Mercury has now crossed the entire face of the sun and brought to a close the 2016 transit of the smallest planet in the solar system. The images astronomers have taken today have been truly breathtaking. I hope you enjoyed them as much as we did here on the (somewhat geeky) science desk.
As Dr Marek Kukula, public astronomer at the Royal Observatory in Greenwich, put it, the transit is a special event: “It’s a chance to feel you are really part of the solar system in motion.” Thanks to all who watched with us. And see you again in 2019!
A silhouette of a plane and its contrails as seen from Frankfurt on Monday as Mercury passes in front of the sun. The innermost planet of the solar system is the tiny dark dot near the bottom and half way across the face of the sun.
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In half an hour Mercury will have crossed the sun and completed its transit for 2016. Here’s the latest video footage from Nasa’s Solar Dynamics Observatory showing Mercury passing swiftly over the boiling surface of the sun. And not a frozen pea in sight.
Of course, if you can’t get yourself to a high-end telescope with a solar filter, and have had enough of Nasa’s swanky satellite imagery, you can always recreate the transit of Mercury in the comfort of your own kitchen. Here’s what Poppy (aged 6¾) and Rufus (aged 3½) in South London did with a pizza base and a frozen pea. They’ve really captured the drama of the event.
The Flamsteed Astronomy Society is out in force at the Royal Observatory in Greenwich today. Here, society astronomer Mark Duwe, looks to the heavens as the clouds threaten to close in. Read Maev Kennedy’s full report from the scene.
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A few minutes ago I spoke to David Rothery, professor of planetary geosciences at the Open University in Milton Keynes. He spent much of the morning peering through a telescope set up on the university’s Mulberry Lawn. Thanks to a dodgy weather forecast, the much-feared cloud cover failed to materialise early on, making for an exceptional morning of Mercury watching. “It was great to show Mercury’s silhouette to school kids and colleagues, and a thrill for me too given I’m involved in the next mission to fly there,” he said, the mission in question being BepiColombo, due to launch in 2018.
Jim Green, Nasa’s director of planetary science, has been talking on Nasa TV about the transit and Mercury itself. It’s hot enough to melt lead on the surface of the planet, but at the north pole there are craters with regions that are in permanent shadow. “We believe there is water and other volatiles in these permanently shadowed craters,” he said.
And here’s a gorgeous gallery of images from around the world:
We’ve put a up a few pictures from readers, but the GuardianWitness team have picked out their favourites sent in so far.
Alan Pickup of Guardian Starwatch fame has snapped his own fabulous picture of Mercury winging its way across the sun like a small, spherical Roman God.
Mercury in transit. Canon DSLR with 300mm lens and Baader solar film. pic.twitter.com/BkbqjtLveh
— Alan Pickup (@alanpickup) May 9, 2016
More footage from Nasa’s Solar Dynamics Observatory high up above the Earth:
Solar Dynamics Observatory captured this view of the #MercuryTransit this morning! More at https://t.co/F2DCjnjUN5 pic.twitter.com/pyQPC2MBXF
— NASASunEarth (@NASASunEarth) May 9, 2016
At the Royal Observatory in Greenwich, my colleague Maev Kennedy has grabbed a shot of the Great Equatorial Telescope trained on the sun for the first time since 1927. She is with astronomer Tom Kerss who is incredulous with delight that despite the forecast of 100% cloud cover, the skies above London have been dazzling.
Amateur astronomers in Germany watch the transit from the grounds of the Bergedorf observatory in Hamburg.
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But back to today’s transit. Here are some more pictures of Mercury taken by our readers. First up, this wonderful shot fromTim Easley in South London. He used a 200mm lens and an ND400 filter. Mercury is visible as the small, black spot on the left side of the sun.
Another picture here from Alex Bailey:
And a brave - if not wholly successful- attempt to capture the transit with an iPhone through a telescope at the University of St Andrews:
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Nasa’s Messenger spacecraft took some truly breathtaking pictures of Mercury. In the image below, the lowest regions are shown in purple, and the highest regions in red. The difference in elevation between the lowest and highest regions is about 10km. Prominent features are the smooth northern volcanic plains and the enigmatic northern rise. The low-lying craters near the north pole are home to “radar-bright” materials, thought to be water ice.
The image below is an enhanced colour mosaic which shows craters on Mercury ranging from 30 to 50 miles wide in the Caloris basin.
In an hour’s time, Mercury will be halfway across the face of the sun. The first observation of the transit was documented in 1631, an impressive feat given that the planet is only 3000 miles wide - roughly the size of the moon - and 48 million miles away.
The surface of the planet is covered with basalt from ancient volcanic eruptions. But over the top of the volcanic rock is a good layer of dust much like that seen on the moon. Walk about on Mercury and you’d leave footprints on the ground. Other features on the surface are curious “hollows” that plunge down 20m or so. They are thought to be made when material sublimates off the surface, but it’s not clear why the copious dust on the ground doesn’t fall in and cap the hollows.
We should learn more when the joint European-Japanese mission, BepiColombo, heads to Mercury in 2018. The two spacecraft are due to arrive in Mercury’s orbit in 2024 and make the first details maps of the planet’s minerals and other elements.
And just in case you needed reminding...
#MercuryTransit Safety: DON'T LOOK DIRECTLY AT THE SUN. Use a solar filter made of specially-coated glass or Mylar pic.twitter.com/bXo94Gk531
— NASA (@NASA) May 9, 2016
Better still, go to a public event organised by astronomers who have the right filters set up on their telescopes.
A fire drill at City University of New York has bumped up viewing figures...
#mercurytransit viewing outside York CUNY + fire drill = massive #astronomizing pic.twitter.com/asRWyroA9I
— Bk Pretty Telescope (@PrettyTelescope) May 9, 2016
Astronomers at the Birla Planetarium in Chennai, India, capturing the transit today.
The GuardianWitness callout to readers has yielded its first pictures of the transit! This photo from Stephen Jennette in Morecambe was taken through a Lunt 60mm solarscope. That tiny black spot at the very top of the image looks like Mercury soon after first contact.
Not all of our readers had such luck, mind. Scott Dougall had a tough time resolving Mercury. No one said this astronomy lark was easy!
Thanks to Scott and Stephen!
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Here’s a snap of Mercury from one of our commenters, Pogofish. Thanks!
Here is how the Manchester Guardian covered the transit of Mercury in November 1907.
The US space agency has put together images from the Solar Dynamics Observatory into this short video showing Mercury embarking on its journey across the sun:
#SDO has a front-row seat to the #MercuryTransit! For more footage, check out https://t.co/5OFdcyOFJ8 pic.twitter.com/2AUzrJx3mz
— NASASunEarth (@NASASunEarth) May 9, 2016
This is how Nasa’s Kepler space telescope measures the brightness of far away stars in the search for alien planets. The dimming produced by a transiting planet is incredibly small unless the planet is massive and on a tight orbit. When astronomers detect signs of transiting planets, they often turn to other telescopes to confirm the discovery.
Telescopes on the ground and in space are capturing clear images of Mercury as it passes in front of the sun. But the same orbital process is used by astronomers to spot planets around stars far beyond our solar system. Astronomers have identified about 6,000 candidate planets around distant stars, and most of these betray their presence when they cross in front of their parent stars, and make them dim ever so slightly. By recording how regularly the starlight dims, astronomers can work out the length of a year on each planet they find.
This is the first transit of Mercury for a decade. While the planet completes an orbit of the sun fabulously quickly, in only 88 days, Mercury usually swings too high or too low for it to cast a shadow on the Earth, and so be visible on the sun’s disc. The next chance to catch the transit is in 2019, but in the UK, today will be the best opportunity until 2049. Only Mercury, the first rock from the sun, and Venus, the second, can be see wandering across the sun from Earth, the third rock from the sun.
One of the many bonuses of live blogging perhaps the slowest events in the known universe is the time it gives one to ponder the ways astronomy has shaped modern arts and culture. But never mind that. Before Sting became head of yoga he was in a band called the Police and they performed this song. I don’t believe it’s about the transit of Mercury. Honestly, I have no idea what it’s about. Apart from pain.
Nasa, of course, crashed a spacecraft into Mercury last year. The impact, an intentional one I should add, marked the end of the highly successful Messenger mission. The probe was the first to go into orbit around the solar system’s innermost planet. As it swung around the planet, Messenger mapped the surface of Mercury in unprecedented detail. The model of the terrain scientists have created from the images is quite stunning:
Although a day on Mercury lasts for two Mercury years, that doesn’t mean eight seasons in one day. Unlike other planets in the solar system, Mercury isn’t measurably tilted on its axis, so one time of year is much like any other. When astronomers talk about the seasons on Mercury, they mean the difference between the hot face, which is facing the sun at the time, and the slightly less hot face, which is facing away. The temperature on the planet reaches more than 400 Celsius, so not much hope for liquid water or life as we know it.
And here is another snap rom Nasa showing Mercury as a little black dot moments before it passes in front of the sun:
From 10 minutes ago -- Mercury prepares to enter in front of the sun's disk! More at https://t.co/5OFdcyOFJ8 pic.twitter.com/lKPGGxTUpo
— NASASunEarth (@NASASunEarth) May 9, 2016
Images have started to come through from Nasa’s Solar Dynamics Observatory. This picture, taken in the extreme ultraviolet range of the electromagnetic spectrum, shows Mercury crossing the boundary of the disc at the start of its journey across the sun’s face.
And the #MercuryTransit has begun! #SDO caught this image of ingress in extreme ultraviolet light about 20 min ago! pic.twitter.com/0o8ks9btU3
— NASASunEarth (@NASASunEarth) May 9, 2016
Mercury doesn’t have much of an atmosphere. Instead, the wispy gas around the planet is called an exosphere. This cloud of atoms is so tenuous that the solar wind blasts it from the surface and out into space, where it forms a comet-like tail hundreds of thousands of miles long. Nasa scientist Rosemary Killen is taking advantage of today’s transit to study Mercury’s exosphere, by analysing light from the sun as it passes through on its way to Earth.
The transit of Mercury has huge historical importance. When the English astronomer, Edmund Halley of comet fame, watched the transit from St Helena in 1677, he realised it would be possible to use transits of Venus - a larger planet that is closer to Earth - to embark on the process of measuring the cosmos. Observers set far apart on Earth’s surface could time the transit and then, knowing the distance between them, work out the distance from the Earth to the sun. With that measurement in hand, astronomers could move on to calculate the distance to the nearest stars.
Judging by this astronomer’s reaction, the transit is going well so far. This from the Guardian’s Maev Kennedy at the Royal Observatory in Greenwich:
“Oh wow, it’s on, it’s happening, I can see it clear as day” said astronomer Roman Gerasimova, momentarily losing his scientific cool as the tiny black dot appeared through his telescope, five minutes earlier than he expected it to be visible from his viewpoint. The first members of the public to see it were two tourists from the Czech republic, Martin Kalab and Ivana Leopoldova, who read in their Czech newspaper that it would become visible from 1.07 - when they would be heading for the airport, and arrived at the Observatory as the last stop of their four day holiday to realise that because of the hour difference they were brilliantly on time. “It is a coincidence - but we are so pleased to see it “ she said. Roman’s telescope is filtered only to see the hydrogen elements, so the sun appears as a spectacular blood red disc.
A manuscript note in the Royal Society Library hints at an observing program that would eventually transform our ability to predict the motions of the planets, writes Karl Galle on the Guardian’s H word blog today:
“Today I saw Mercury.” This terse remark scrawled inside a 16th-century almanac could reflect anyone watching today’s transit of Mercury across the Sun. The winding path this observation took after it was recorded, however, traces a century-long story leading through the transformation of both our understanding of the cosmos and the practice of astronomy itself.
The Great Equatorial Telescope at the Royal Observatory in Greenwich has captured the moment perfectly. Remember, Mercury is passing in front of the sun at about 30 miles per second. But it will take more than seven hours to reach the other side.
#mercurytransit through our Great Equatorial Telescope, tune in live https://t.co/nC5YwOD5Mq pic.twitter.com/EYr9WTc7ou
— Royal Observatory (@ROGAstronomers) May 9, 2016
And here is Mercury, just inside the outer edge of the solar disc. The moment of second contact:
And there it is! Second contact! @Slooh #MercuryTransit pic.twitter.com/acAVQ6G5Cq
— Carl Franzon (@carlfranzon) May 9, 2016
The transit has started!
The transit has begun! Great footage coming in from various telescopes around the world. The French feed here has just shown what looks like “second contact”, the moment Mercury is entirely inside the disc of the sun:
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Royal Observatory astronomer Brendan Owens says:
I’ve been refreshing the Met Office app all weekend - they were giving cloudy and getting cloudier, but here we are in bright sun under a blue sky, it’s perfect. Several of their astronomy society members have brought large filtered telescopes for the public, but the provisions for the free public event include two Heath Robinson-ish contraptions, viewers which reflect the image captured through a lens focused on the sun, one made of cardboard, one of chipboard, both working perfectly. The event goes on for 7.5 hours. We’re going to keep moving these tracking the sun until we reach the very furthest balcony we have tonight - we’re going to squeeze the last drop out of it.
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And here’s Dave Rothery from the Open University, all ready to watch the transit:
#mercurytransit looking good @OpenUniversity don't forget #mercurytransitselfie pic.twitter.com/Z9Ph7EFLPe
— David Rothery (@daverothery) May 9, 2016
My colleague Maev Kennedy is at the Royal Observatory in Greenwich to watch the transit which begins in a few minutes from now. She writes:
Astronomer Dhara Patel with the Royal Observatory’ s sophisticated cardboard transit viewer - through which a sunspot larger than the earth is already visible.
Mercury is a really, really strange planet. You wouldn’t want to spend your birthday there, but if you did, you’d at least get to celebrate twice a day, thanks to the planet’s rotation and orbit around the sun.
The Open University have put out this lovely video that explains all:
Hurry and you can still make it along to one of the many transit parties being held by astronomy groups around the country and worldwide.
The Royal Astronomical Society here in the UK has compiled a list of events is here. And the European Space Agency has its own list here. Nasa’s Jet Propulsion Lab has pulled together another list of transit parties in the US.
The smallest and fastest planet in the solar system will cross the face of the sun today and from many parts of the world the whole transit will be visible. All of the UK, most of Europe, and much of the Americas will have the chance to watch from start to finish, with only Australia and far east Asia missing the spectacle, because for them the event takes place at night.
The transit begins at 12.12 BST and ends at 19.42 BST, when the small black dot of Mercury will slide free of the sun’s disc. We will be following the transit live through the day, with rolling footage from the ground and from satellites trained on the sun. Remember that looking directly at the sun can cause permanent damage to the eyes. For this event, astronomers on the ground are using telescopes fitted with special solar filters that make the sun safe to view.
The transit of Mercury happens only 13 or 14 times a century. This will be the best chance to watch the event from the UK until 2049. Join us!
Here it is from Aberdeen at 12:32:
http://cdn.ipernity.com/200/17/40/41831740.8cc5acaa.jpg