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Sunday, 3 June 2012

Venus, dark twin of Earth, in the light.... and behind the clouds

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Image above: The last transit of Venus, as seen by the TRACE spacecraft [1]. You can just about make out the light refracted through the edge of the Venusian atmosphere, completing the circle of light around the planet. Image courtesy of NASA/JPL.

The problem with last-chance-to-see-this-lifetime astronomical events, is that space ship Earth sometimes won't co-operate.Or put another way: Tomorrow is the beginning of the transit of Venus [2] across the Sun. It's the last time this will happen for over a hundred years. Work wouldn't give me Tuesday off, and the weather here in Manchester is.... well, it sucks at the moment.

So, since it doesn't look like I'll get a chance to see the transit myself, I'll content myself  by offering a piece of advice you'll hear from every good astronomy website:

DON'T  look directly at the unfiltered sun. And DON'T EVER look at the sun through a telescope or binoculars. It's a thermonuclear fireball three light seconds wide, don't forget that.

If you need any further convincing of its power to burn your eyeball out of your head (I'm not exaggerating in the slightest) when focused to a point, watch this video:

Video above: This is what sunlight can do. A small telescope won't have quite this much power. That doesn't matter, as it won't need a thousandth of it to blind you for life. Be very bloody warned. Video courtesy of the BBC.

The other star of the show isn't a star, it's Venus. Which is a planet. Although you probably knew that.
A quick internet trawl will provide you with all sorts of delightful facts about Venus:
The surface is a four hundred degrees Celsius, 90 atmosphere, pressure cooker of a hellscape. It spins backwards. The clouds are made of sulphuric acid and form what looks like a planet wide hurricane centred on the south pole. It's a fascinating world, although no garden spot. What makes it fascinating are the mysteries and questions still surrounding it, which are far to many to list completely at gone midnight.
So, to get you started on finding out about them for yourself -  the best way to find things out - here are few less well known facts about Venus:

Image left: The change in temperature and pressure with height above the surface on Venus. Temperature is given in degrees Kelvin, which means water freezes at  273 degrees on this scale. Image courtesy of Pearson Prentice Hall, Inc

1: About 55 Km above the surface the temperature and pressure are the most Earth like anywhere in the solar system.

2: It has been theorised that the planet formed from a head on collision [3]between two protoplanets.

3: There are signs of active volcanoes on the surface [4].

4: The entire planet seems to have resurfaced itself [5], in a titanic outpouring of lava, three to six hundred million years ago

5: There are mysterious bright clouds [6] that appear in its atmosphere, sometimes spreading to cover most of a hemisphere.

6: Having no magnetic field [7], the solar wind crashes straight into the upper atmosphere.

7: Billions of years ago, Venus is thought to have been an ocean bearing planet [8].

Image right: Venus in UV light, as seen by the Venus Express spacecraft. Image courtesy of ESA.

8: The clouds are threaded with streaks of an unknown compound that absorbs UV light [9].

9: It wasn't confirmed that the Venusian clouds produced lightening [10] until 2007, proving that lightening doesn't need atmospheric water vapour to happen.

10: The Akatuski space craft [11], launched by JAXA to study the planets atmosphere and climate, suffered an engine malfunction as it tried to pull into Venusian orbit in 2010. But JAXA engineers are both inventive and determined: The probe is making another attempt to enter orbit in 2016, using only it's manoeuvring thrusters.

Go one, do some more reading on Venus! It may be a bad, baaaad, spot to visit in person, but it's a constantly changing, incredibly complex, active planet. Give this acid soaked, lead melting, incredible planet a chance to enthral you. From a distance.

Good luck watching the transit of Venus tomorrow and Tuesday, let me know how it goes, and what you're able to see!

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