EYES ON THE NIGHT SKY: JULY 2018
This month, the night sky remains in deep twilight, therefore, it is still not dark enough for studying deep space objects. However, there are some great opportunities to catch some planetary action during the month of July. The first week of this month is an excellent time to see Noctilucent Clouds, so remember to look towards the north on a clear night, two hours after sunset.
Mercury sets 90 minutes after sunset – look low on the west-northwest horizon, in the four o’ clock position to Venus. It is the most difficult unaided eye planet due to its proximity to the Sun. It is currently in phase, so it is best viewed with a telescope. Try finding it at around 9.30pm as the Sun sets.
Mars is at Opposition on 27th July which means the Red Planet and the sun are on directly opposite sides of the Earth. July is an exciting time for this planet as not only is it closest to Earth on 31st July, it shares a fascinating conjunction with the Moon, which will be experiencing a partial eclipse by the time we see it as it rises from 9.30pm.
Both objects will appear reddish. The ‘closeness’ of Mars allows us good views of the planet’s surface but its highest position will be 13° above the horizon, which may mean views may be spoiled by atmospheric turbulence. At -2.8 magnitude, Mars will appear brighter than Jupiter.
The New Moon occurs on 13th July and the Full moon on 27th July. The partial lunar eclipse occurs on the same date as the Full Moon. The full lunar eclipse will be visible from Australia, South America, Asia, Areas of Europe and Africa but by the time it rises in the UK it would have moved out of maximum eclipse. Nevertheless, it is a fascinating phenomenon to watch.
Jupiter continues to dominate the night sky and is a fascinating object to study with the dance of the Jovian Moons. Look out for the Great Red Spot, which is a massive anticyclone, twice the size of Earth with maximum wind speeds of 200 mph. First discovered in 1830, studies into this phenomenon has revealed some very strange facts about this gigantic storm. For example, the storm travels westwards, against the gas giant’s eastward rotation, as evidenced by the animated image below (Credit: NASA):
In addition to this, the redness of the Spot has been fading to an orangey hue since 2014 - which may be caused by ultra-violet radiation from the Sun as the storm grows taller. From our perspective, the Great Red Spot appears to be shrinking when it is actually becoming more compact. With reliable observation records going back to 1878, the Spot has shrunk to a third of its size.
If you would like to study the Great Red Spot, here are the times in the UK you can see it (British Summer Time):
1 July - 1:02
3 July - 22:32
8 July - 21:41
10 July - 23:19
15 July - 22:28
20 July - 21:37
22 July - 23:16
27 July - 22:25
See you next month when Astronomical Darkness starts during the first week of August and the exciting Perseid Meteor shower peaks on 13th August.