Opposition of Neptune

On August 29th 2014, Neptune will be at Opposition. It will be at its highest at 1:11BST, rising at sunset. However, it will probably be best to wait until 22:37BST or later to view it. That’s when its at least 20 degrees above the horizon and so out of the worst of the atmospheric haze. It doesn’t get very high as the map below shows:

Clear skies.

A good time to see a comet

Two comets are on good view to those with binoculars or a telescope.

Comet Jacques (C/2014 E2) is currently working its way across the sky. For the next few days it will be moving out of Cassiopeia and across Cepheus as shown in the map below (green line is the comets position between 25th August and 1st September. Now is a good time as the Moon will be out of the way.

Comet Jacques is around magnitude 7 and is expected to stay that for a while yet, so you will need binoculars at least to see it. Large telescope owners may be able to make out a pale green colour and see its faint tail.

For the early birds amongst you Comet Oukaimeden (C/2013 V5) is visible just before sunrise. It is fainter than Comet Jacques at magnitude 8.5 or so and is very low on the eastern horizon. It will get lower over the coming days so get out quick if you want to have a look at it.

Clear skies.

Jupiter and Venus conjunction

On Monday 18th August, Jupiter and Venus will be in close conjunction in the early morning sky. Closest approach is around 05:00AM UT, or 6:00AM BST. They are going to be very close (0.2 degree) in the NEE. See the map below:

The map shows the morning sky for 5:30AM BST on the 18th August in the UK. Jupiter and Venus are only 10 degrees above the horizon so you’ll need a clear horizon. By 6:00AM they’ll be at 14 degrees.

If you have a very clear horizon, then before sunrise you should be able to get Jupiter, Venus and the Beehive cluster in binoculars or a wide field telescope. But they will be very low, only a few degrees above the horizon.

Clear skies

Perseid meteor shower

This year the Perseid meteor shower peaks at 0 hours UT on the 13th August. Unfortunately there will be an almost full Moon in the sky as well, which will hide the fainter meteors. However, bright ones might still show up. If you do go out to have a look, then have something to sit on so that you can comfortably see a good chunk of the sky. See the map below. The map marks the radiant, the point where all the Perseid meteors appear to come from. Don’t look in this direction as the meteor trails will be much shorter. Look further east or west of this point. Although it is summer, sitting outside in the dark, you will get cold so make sure you have a blanket and warm clothes.

You don’t need any special equipment to see the meteors. The peak of this shower lasts for a long time so you will likely see enhanced activity at any time after dark on either the 12th or 13th August.

Clear skies.

A summary of February’s main meeting

Dr Colin Wilson of Oxford University showed us how modern technology could be both a curse and a blessing when he couldn’t get his planned talk to work, so he quickly accessed the university online and downloaded two Venus talks from his database…and melded them beautifully.
‘The Cloudy Veil of Venus’ dealt with our knowledge of Venus over time, followed by ‘The Case for Venus Exploration’.

Venus is the most Earthlike of the planets and is our nearest neighbour.  Visual images of Venus are bland.  Ultra-violet images are much clearer and show the upper atmosphere rotating every four to five days, while the surface takes 240 of our days to perform a full rotation.  That is a factor of 50:1.  (He compares it to our jet stream, which orbits ten times faster than the Earth’s rotation.)  Earth-based UV studies use wavelengths between 280 and 200nm.  The shorter wavelength gives you more contrast but the planet’s heat and minimal magnetic field makes it difficult to observe.
According to Dr Wilson Pythagoras could see the phase of Venus so was able to conclude that the universe was Sun-centred.
The Venus Express spacecraft is the only craft out there at the moment.  It is Europe-run and arrived in 2006.  It has a highly elliptical orbit, which takes it from 66 to 200km from the surface.
But, the first Venus missions date from 1961 – very early in the space race, but there were lots of failures until Mariner 2 (Nasa, 1962) managed a flyby and detected its incredible heat – a surface temperature of 4500C.  Until then in was thought Venus was a watery world, but of course we now know it has suffered from a runaway greenhouse effect.
Later craft such as the Russian Venera probes and the Magellan radar mapper discovered the surface to be volcanic.  The original Venera images were very orange but when colour corrected to white light the surface is very dark.  (Don’t forget also that only 2% of light gets through to the surface.  Remember the Moscow in a thunderstorm at midday analogy.)
Mariner 10 in 1978 originally detected the polar vortex, which is constantly changing shape and sometimes is three-sided (so not quite as odd as Saturn’s six-sided polar vortex).  You would see it as a hole if you were overhead.
Dr Wilson asks are the volcanoes active.  Thermal infra-red imaging indicates that some are hotter than the surrounding areas, but that they have not been active for a million years. However, some hot patches have recently been detected in the volcanoes, but that information is not yet published so I’d better shut up about that. 

Russia is planning to land another craft on Venus but not until 2022 and it will be getting some help from Japan and the USA.  How things have changed.  A new Venus radar will be able to give a spatial resolution of one to five metres (compared to Magellan’s 100m at best). The surface of Venus is about one billion years old.  It is dated by using the proportions of noble gases detected.

I’d like to add, in case you do read all that, that you can catch the phase of Venus in the morning but that Venus is becoming more gibbous and smaller by the day.  (That should be elsewhere in Spacewatch thanks to Bob.)

Gwyneth Hueter.

Abingdon Clubs and Societies day

The society has a stall at the Abingdon Clubs and Societies day which takes place tomorrow (29/3). This takes place at the Guildhall, Abbey Close, Abingdon, OX14 3HL, from about 10am onwards. It usually ends about 4pm. 

If you’re in Abingdon then do drop in and say hello. If you can spare an hour to help out on the stall that would be great and much appreciated.