It’s been a long time since I lasted posted a blog entry. It
hasn’t been a great year so far with precious few observing opportunities
around. The cloud has felt nearly constant for the first quarter of the year,
but there have been a few chances to get out under the stars in between. The moral of the story is to not get downhearted and, even if it's only half an hour, grab the opportunities while you can!
This week is a great one to really make an effort, if the
skies clear, because this week sees Mars at Opposition. That means it makes its
two-yearly closest approach to Earth, so appears at its largest in our skies.
The next one isn’t until 2016, so if you get a chance to get out and observe,
make Mars your priority target.
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| Photo by NASA |
The Red Planet has long been a tantalising object – its colour
gave it an association with the God of War, and Holst certainly agreed when he
wrote the portentous opener to the Planet’s Suite, “Mars, Bringer of War.” It
became the abode of alien intellects “Cool and vast,” according to H. G. Wells in
“War of the Worlds,” and swiftly became the place where green men from outer
space would come from for a spot of invading. Later on things got a little less highbrow with Irish
rock band Ash celebrating a “Girl from Mars” and Tim Burton’s execrable “Mars
Attacks!” film. Even now Mars holds a certain fascination with us on Earth, and
as I type a number of missions are underway on and around its surface.
Why Mars is so interesting is open to conjecture. It's about half the size of Earth (Venus is nearly the same size as us) and in distance
terms it varies from around 0.6 AU to nearly 2.0 AU from us (Again, Venus is closer...). And yet it may
have harboured life at some point in the past, or even now. There is much
evidence of liquid water on its surface, with huge river canyons carved through
the dusty red landscape. It has ice-caps like our planet, although they are
made of dry ice, solid carbon dioxide. And interestingly it has active
volcanoes, including the highest mountain in the solar system, Olympus Mons, of fundamental importance in the creation of an atmosphere.
Any discovery of life, past or present, would be profound for us, taking away
Earth’s special place as the abode of life in the universe.
Unfortunately, as far as observational astronomy goes, it isn’t
exactly a thrilling target, usually looking like a small orange disk with no
discernable detail whatsoever. To add to the fun it has frequent dust storms
raging across its surface that mask the features with even more impenetrable
orange. In short, Mars is one of the most disappointing things you will view
through a telescope – unless that is, you give it the time it needs.
Naked Eye
Mars is currently rising at about 20.30 BST. I wouldn’t
recommend trying to observe it until about 22.30 though, because it suffers
from atmospheric disturbance. If you’re just aiming to find it by eye then its currently
in the constellation of Virgo – you find it by following the handle of the
Plough down to Arcturus then carrying on to another bright blue star called
Spica. Mars is pretty close to Spica in the sky and a similar brightness to
Arcturus – in fact the two are easy to mistake. The difference is that Mars, as
a planet, won’t twinkle and will appear slightly more orange.
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| Image thanks to Stellarium |
Binoculars
Through binoculars there isn’t an awful lot to see. It will
appear as a small orange disc. This opposition is rather unfavourable so the
planet will only show about a 15’’ disc and will appear very unspectacular.
Still, this is where the aliens came from in War of the Worlds, during an
opposition, so if you think you see cannon-fire on the surface, avoid Woking.
Telescope
Through a telescope the view is… craptastic is probably the
best word. To see anything you have to ramp up the magnification something
chronic – x200 is the usual recommended minimum and that happens to be around the
average limit of seeing from UK skies. My ST80 is limited to about x80 with the
equipment I have, so I may as well use my binoculars. I now have a 6’’ Dob (The
trolley Dob!) which will give me up to x300, although even at x150 I can see a
few of the planet’s secrets. Probably the easiest feature to see is the
Southern Polar Cap which is angled towards us at present. You should also be
able to get dark patches on the surface – the largest of these is called Syrtis
Major. If the seeing is stable, make sure you spend a bit of time at the
eyepiece with Mars because it takes a bit of time and effort to see anything.
Of course when you do, that feeling of achievement is all the better!
That’s your lot for this time. I promise not to leave it so
long until the next one…
