How to see the planets in the night sky, August 2020

Mars reaches opposition in mid-October, a time when it appears largest and brightest for the current period of observation.  A planet is said to be in opposition when the Earth lies directly between it and the Sun.

The last Mars opposition was poor as seen from the UK since it was never all that high, but this time it occurs at a greatly improved altitude, which is all the more exciting.

During August Mars builds on the already impressive performance boost it got in July. Last month it moved from a compromised morning location to one where it appeared high in the sky in twilight.

This month it manages to reach its highest position due south, in true darkness.

On 1 August Mars shines at mag. –1.1, displaying its beautiful salmon-pink colour to the fore.

Through a telescope it shows a 14 arcsecond disc on 1 August. The disc appears gibbous lit, with a phase of 86%.

On the morning of 9 August a 73%-lit waning gibbous Moon can be seen close to Mars. As the sky begins to brighten on the morning of the 9th, both objects are a fraction over 3˚ apart.

If you can stay with them throughout the day, then just before they set – say around 11:00 BST (10:00 UT) – the separation will be just over 1˚.

This is in daylight, of course, but at mag. –1.3, Mars should still be visible with an optical aid, given clear skies.

By the end of the month, Mars nestles within the ‘V’ pattern representing the cord tying the two fish together in the constellation of Pisces.

This position allows the Red Planet to reach its highest position of 43˚, due south around 04:15 BST (03:15 UT) while the sky is still dark. On 31 August Mars will be shining at mag. –1.8 and presents an 18 arcsecond disc when viewed through a scope.

How to see the planets this month

Mars

• Best time to see 31 August, 04:00 BST (03:00 UT)
• Altitude 43˚
• Location Pisces
• Direction South
• Features Dark ‘albedo’ features, polar caps and weather
• Recommended equipment 150mm or larger

Mercury

• Best time to see 1 August, one hour before sunrise
• Altitude 3˚ (very low)
• Location Gemini
• Direction Northeast

Mercury was at greatest western elongation on 22 July, visible in the morning sky. At
the start of August, it appears to head back towards the Sun, rising later with each passing day.

On the 7th, Mercury is at mag. –1.3 above the northeast horizon, rising 70 minutes before the Sun. It’ll probably only be possible to catch it for a few days after this; superior conjunction occurs on the 17th, after which Mercury reappears in the evening sky.

Venus

• Best time to see 31 August, 05:00 BST (04:00 UT)
• Altitude 24˚
• Location Gemini
• Direction East

At the start of August, Venus rises three hours before sunrise. A brilliant morning beacon, it shines at mag. –4.3. Through a scope Venus appears 43%-lit and 27 arcseconds across.

On the morning of the 15th, Venus appears close to an 18%-lit waning crescent Moon.

The planet reaches greatest western elongation and dichotomy – geometrically 50%-illuminated – on 13 August (see page 43). On 31 August, mag. –4.1 Venus rises four hours before sunrise. Through an eyepiece it presents a 59%-illuminated gibbous disc.

Jupiter

• Best time to see 1 August, 00:00 BST (23:00 UT)
• Altitude 15˚
• Location Sagittarius
• Direction South

Jupiter remains well presented during August, having reached opposition last month. Unfortunately, from the UK it remains low for telescope views.

However, it does manage to reach its highest position in darkness all month long. Jupiter shines at mag. –2.6 at the month’s start, dimming marginally to mag. –2.4.

Saturn

• Best time to see 1 August, 00:30 BST (23:30 UT)
• Altitude 16˚
• Location Sagittarius
• Direction South

Like Jupiter, Saturn was also at opposition last month. It’s currently located just east of Jupiter, and like its gas giant neighbour, remains low from the UK.

Saturn shines at mag. +0.5 at the month’s start, dimming to +0.6 by its close. The full Moon lies nearby on 2 August, and an 89%-illuminated waxing gibbous Moon revisits the planet on 29 August.

Uranus

• Best time to see 31 August, 04:00 BST (05:00 UT)
• Altitude 49˚
• Location Aries
• Direction Just east of south

Morning planet Uranus almost reaches its highest point due south in darkness by month’s close. It’s on the threshold of naked-eye visibility at mag. +5.7.

Neptune

• Best time to see 31 August, 02:00 BST (01:00 UT)
• Altitude 32˚
• Location Aquarius
• Direction South

Morning planet Neptune improves in appearance over the month, reaching its highest point due south in darkness from the middle of month onwards. It shines at mag. +7.8 and requires at least binoculars.

Pete Lawrence is an experienced astronomer and co-host of The Sky at Night. This article originally appeared in the August 2020 issue of BBC Sky at Night Magazine.