The planets
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
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.
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.