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.
Mercury through a 10 inch telescope
The planet Venus is a brilliant morning star at the moment. Catch it rising in the south east ahead of the Sun between 5.30am and 7.30am.
With keen eyesight and binoculars you should be able to discern Venus’s phase, currently a beautiful crescent. A telescope will make this much clearer as demonstrated by this video footage I shot last year, when Venus was ‘the evening star’.
Over the month of November Venus will get brighter as its phase waxes from a thin crescent to a 25% illuminated disc at month end. Despite this brightening Venus is actually travelling away from us and after December 2nd its brightness will begin to diminish as it pulls further away from earth and its disc size shrinks .
Once Venus passes behind the Sun it will eventually reappear as an evening star around mid August 2019.
Heavily cratered Mercury
If you have flat and unobstructed views towards the south west there’s a chance of observing one of the most elusive planets this evening – Mercury.
Mercury is hard to see because it orbits so close to the sun, meaning it’s usually lost in the glare of our parent star.
However the planet is currently at its maximum eastern elongation from the Sun, so there’s a small window of opportunity to spot Mercury just after sunset low in the south west. Grab a pair of binoculars and see if you get lucky.
For us high northern latitude observers it’s a tough ask due to the currently flat orientation of the ecliptic, but even if you don’t see Mercury you should catch Saturn sitting just a little higher on the horizon.
Mercury goes through several peak elongations from east to west during a year, providing alternating opportunities to see the planet in pre-dawn or evening skies
Maximum eastern elongation
Despite being closest to the sun, Mercury isn’t the planet with the highest temperatures – that prize goes to Venus with its thick carbon dioxide cloud base. This is because Mercury has no atmosphere to trap or distribute heat. If you were able to stand on Mercury, your daytime temperatures would be a blistering 427C. However, if you hid in the shadow of a large crater or travelled into the dark half of Mercury, temperatures would plummet to a freezing -173C! Again, due to a lack of atmosphere to smooth out the temperature extremes.
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!