A monthly look at astronomical events in the sky and on Earth
Just a summary of observing this month as our usual contributor is unavailable. As with June, with the long summer days, there is not much opportunity for observing, but there are a few standout events.
The Solar System
Jupiter and Saturn reach opposition mid-July
Both of these planets reach opposition this month and are also close together in the night sky (You can look forward to a rare Great Conjunction of these two planets in December this year).
Watch out for a number of moon events for Jupiter, with several transits through the month.
For Saturn in opposition there is the Seeliger effect, where the rings appear brighter than expected because of the way they line up relative to Earth.
- Best time to view Jupiter: 01:00 BST 14 July
- Best time to view Saturn: from 00:00 20 July
The red planet becomes more visible this month after being hard to see for a while. By the end of the month it will be mag. -1.1 and reach an altitude of 35 degrees. Best time to see: 04:00, 31 July.
There will also be a conjunction of the Moon and Mars on Saturday 11 July at 20:38 BST.
Throughout July, Venus will climb progressively higher into the eastern predawn sky. It rises about 2 hours before the sun in early July, increasing to about 3 hours by the month’s end. As it moves away from Earth, Venus’ waxing crescent phase will widen as its disk size shrinks. It will be at its brightest in the morning sky on or around 10 July.
The other major observing event (weather permitting) this month is noctilucent clouds – and you don’t have to get up in the middle of the night to see them! These are normally visible from late May to early August. The word means ‘night-shining’ – the highest clouds in the atmosphere continue to be illuminated by the sun long after it has set. Look to the northwest about 90-120 minutes after sunset, or northeast before dawn.
More observing news…
For more detail of the night sky in July see the Sky and Telescope website
For action in the satellite and spacecraft world and for up-to-date news, scroll https://www.space.com/32286-space-calendar.html
Clear skies and good viewing.