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Thursday 19 March 2015

Solar storm blindsides Earth, and an unusual eclipse...

The Sun is generally a very nice thing to have nearby, especially because we'd all freeze to death without it. But this week the Sun threw a surprise at us: A combination of events led to a storm of solar particles crashing through the magnetic field that protects Earth. On the ground the only effects are a very slight (very, very, very slight) increase in radiation levels, but 20 or 30 km up the particle storm has been crashing into the upper layers of our atmosphere, resulting in Auroras as far south as the midlands of England. I live in Edinburgh, where aurora are rare but not unheard of. A bright one would be a real treat.... so it was cloudy.
Never mind - for at least some people the view was astounding...

Above: To be fair, from this vantage point you'd probably be so bored with astounding sights that you'd crave mediocre reality tv.... Courtesy of NASA
The eclipse:
Tomorrow is solar eclipse day - but it's only visible as a full eclipse in a few places (check this link to see where), a lot more places will see a partial eclipse. The difference is that this is full:

..... and this is partial:

Both are pretty damn spectacular, here's a good link to follow for safe ways to watch. Follow that link guys - looking at the Sun directly is a good way to hurt your eyes, and never, ever try looking at it through a lens or mirror, for this very good reason:

Above: Remember that Bond villain with the giant space mirror, that melted the ice palace and tried to vaporise Bond in his invisible car? No, I'm not drunk, that was actually the plot, and incredibly the giant space mirror is fairly plausible...

This week's eclipse will be a little bit unusual (having the Sun go out is a fairly unusual event all by itself - but there's more!): As well as being a solar eclipse it will also be a super moon (when the moon is closer than usual to the Earth) and a spring equinox. 

On top of that, eclipses themselves are far weirder than most people realise....

Warped space:
 A full eclipse lets astronomers see how the space surrounding the Sun is warped. The Sun's gravity is enormous - after all it outweighs the entire rest of the solar system 100 times over. That gravity causes (or perhaps is the result of, depending on your point of view) a massive warp in spacetime. During an eclipse it's possible to see stars whose light passes right by the Suns surface to reach us - and we can see that the distorted space around the Sun throws the light off its proper course, making them appear in the wrong positions...

Warped time:
During an eclipse we can look into the space near the Sun's surface - and time runs more slowly there. If you could fly a very heatproof space ship to the suns surface and stay there you'd find that the rest of the universe was running 66 seconds a year faster. Over it's five billion year history this adds up, meaning that the Suns space time warp has pulled it nearly 10,000 years into the past relative to Earth.

They're dying out:
Solar eclipses as we know them are unique to our time: The solar eclipses as we see them today happen because of a weird coincidence - the Moon is 400 times smaller than the Sun, but it's also 400 times closer. but the Moon constantly moves away from earth, at a rate of 3 cm per year, so eventually the moon will be so far away it no longer blocks the Sun's light, and our eclipses will be reduced to weedy things like the ones that happen on Mars due to its tiny moons:

Above: A tiny Martian moon makes a weeny sweet ickle mini eclipse, as seen by one of our robot rovers... Courtesy of NASA

They look even better from space: 
From the space station eclipses look like this:

Above: That's a big shadow. Even for a Game of Thrones finale that's a lot of dark... Courtesy of NASA

It's always an eclipse somewhere (in space): 
The eclipse is caused by the Earth passing through the Moons shadow, so the eclipse is a moving place not just a one off event - somewhere out in space there is always a spot you could travel to where you'd see an eclipse. This something that has been seen by some spacecraft, when their paths take through the right spot...

Bands of shadow
As the centre of the moons shadow approaches, and the sun is just a thin crescent, the air turbulence that makes the stars twinkle starts to affect the tiny sliver of the Sun that remains - this causes huge bands of shadow to race around he landscape as the totality approaches:

Elsewhere in the universe:

Staying with the Moon:
The biggest volcano on the Moon has been mapped using a new technique that measures the radioactive signature of the rocks it produced, and a history of unimaginable power has been found. In its day the behemoth threw radioactive rock hundreds of kilometres from its core...

Volcanoes for Ceres? 
The Dawn mission continues to close in on the Dwarf planet Ceres, and as it does so the debate over the bright spots on the surface is heating up - perhaps in more than metaphorical ways. The Herschel space telescope detected what seemed to be plumes of water vapour over Ceres. Although the telescope could only plot the position of the plumes crudely, if you compare plumes and bright spots... ....voila, they match.

Above: A comparison of the water vapour and the surface map, courtesy  of the folks at
And there's more: The brightest spot is visible as it rotates over the dwarf planets horizon - if it were a bright spot on the crater floor then the crater rim would block it at some point before then, so the bright spot must also be a high spot.. None of this is conclusive, but it is starting to suggest cryovulcanism of some sort - and where there's a cryovolcano there could be liquid water, and if there's liquid water then Ceres would be a habitable world....

News from Rosetta:
This week is the 46th LPSC conference, and there's a lot of new information coming out. The Rosetta team have reported finding long chain organic molecules called on the 67P comet, which suggests a kinship to comets like Halleys comet where the same molecule was detected. They also have a new theory to explain the 'windblown' dunes and other features on the comets surface: The soil of the comet is made of particles either two large or too sticky top be affected by the thin gases of the comets atmosphere, so the team has proposed that a similar effect is being caused by grains ejected from vents and bouncing across the surface

JPL develops helicopters for Mars: 
JPL has always had problems navigating its Mars rovers, mainly because the terrain there is so unforgiving. Now they think they've cracked the problems of aerodynamics in the thin martian air, and plan to develop teeny scouter helicopters to run ahead of the main mission and chart a safe route.

Elsewhere on the internet:

Extremely bright meteor over Loch Ness.

 One in three stars have planets in their habitable zone.

New spaceplane proposed.

Born in sight of a monster.

Ice fueled space drives

Whole new island born. 

'Y' shape floating in Venus's clouds

New map of Mercury

Water on early asteroids?

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