Moon Formation

Modelling suggests the Earth came very close to having a pair of smaller Moons.

According to simulations by Canup and Ida (2014) the Earth came very close to hosting two smaller Moon’s (right) rather than the large single Moon we ended up with (left).

This fascinating ‘what if’ modelling is based on the giant impact hypothesis. A faster rate of rotation of the post impact disk is the main requirement for a two Moon system to take hold.

Of course multiple moon system are very common. Saturn for example has an abundance of them, with the most recent count totalling 82 orbiting bodies.

Colour Image: Artist’s impression of an alien world with two moons by Angela Harburn.

Total Lunar Eclipse 21st January 2019

Look out for a spectacular total lunar eclipse next Monday 21st January, when the full Moon will turn blood red in the sky.  I’ve put together a video guide below with details of the timings for the full event at northern GMT latitudes.

You’ll have to get up early in the morning on the 21st to witness totality, with the best observing times spanning 4.42am – 5.45am.  Set your alarms!

The last total lunar eclipse was only 5 months ago, when I photographed the red Moon briefly emerging from clouds.

Big thanks to Kay Nakayama of Chillscape Art & Music for the accompanying music.

Mercury and Jupiter Conjunction

 

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Have you ever seen the planet Mercury with your own eyes? It’s notoriously difficult to catch being situated so close to the Sun and often hard to pinpoint. You’ll only ever see it as a tiny disc in binoculars, very close to sunrise or sunset.

Over the next couple of days, centred on the Dec 21st solstice, there’s a unique opportunity to see Mercury as it forms a conjunction with bright Jupiter low in the south east in morning skies.

You’ll need a good unobstructed horizon to the SE to catch it. Use Venus as a guide to first find Jupiter, then look through your binoculars and you should see Mercury sitting above.

The window is pretty narrow, from around 7.30pm to 8.30pm. The longer you wait the higher Mercury will rise but the brighter the sky, as the Sun rises.

Good luck and clear skies.

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Mercury through a 10 inch telescope

Venus

Venus has been a constant jewel in the evening sky recently, popping into view during twilight in the south west and burning with an astonishing intensity in the western skies after darkness.

I’ve been taking my telescope out a few evenings in a row to view the planet from kerb side and marvelled at how well resolved it is at high power.  It’s a half crescent right now, revealing a lovely hazy terminator where Venusian day meets night.  Eager to record its majesty,  I trained my video setup on it this evening, using leg stabilisers and a barrow to maximise the surface area per pixel captured on my Samsung’s CCD chip.  Here’s what I captured.

The visual scale of Venus is impressive here compared to general viewing with eyepiece observation.  This is one of the advantages of having a smaller CCD sensor.  Whilst more limited for large deep sky objects (without focal reduction) it permits big and bold presentations of the planets with just a modest x2 barlow lens.

Notice the pronounced atmospheric haze and refraction of light at the terminator between day and night.  Venus has a thick cloud covered atmosphere which is highly reflective – giving the planet its bright white appearance.  There’s also the slightest hint of mottling or streaking on the surface.  These fine streaks are large cloud structures that ebb and flow slowly within the Venusian atmosphere.

Not so long ago Venus was the target for many pulpy science fiction stories.  These authors imagined the planet full of swamps with dinosaurs and primitive tribes battling across vast continents.  These fantasies were shot down after robotic probe and satellite recognisance of the planet was undertaken, first by the Soviets and later NASA.

Our current understanding of Venus is that it’s a planetary embodiment of hell.  An atmosphere of nearly 96% carbon dioxide traps heat from the sun, raising the pressure to 92 times that of earth, with surface temperatures approaching those inside the finest Italian pizza ovens.  This pizza analogy would apply to any human making it all the way down to the surface of Venus!