See Neptune in the night sky throughout October 2022

Neptune was at opposition in the middle of September 2022 and remains very well placed for observation from the UK throughout October.

By the end of the month, shining at mag. +7.8, Neptune and mag. –2.6 Jupiter will appear separated by just 6.7˚, both planets being located below the faint Circlet asterism in Pisces.

The separation continues to reduce into next month, reaching a minimum of around 6.1˚ in late November.

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Can you really see Neptune in the night sky?

At mag. +7.8, Neptune is too faint to be seen with the naked eye, theoretically being the only one of the main planets of the Solar System that needs optical assistance to see.

In reality, it’s difficult to spot Uranus too, which often lurks on the threshold of naked-eye visibility, and binoculars are your best choice to try to secure a view of both worlds.

Through a 75mm telescope at high power, it’s possible to get a feel that Neptune’s blue-hued dot isn’t a star, but a larger scope, say over 150mm diameter, is recommended to confirm this view.

If you suspect you’ve got it in your field of view but aren’t sure, centre it and gradually increase the power.

If the atmospheric stability (seeing) is poor, don’t go too high with the magnification. A power of 150x or more should reveal Neptune as a planet.

The larger the aperture you use the easier it will be to see Neptune’s tiny 2.4-arcsecond disc.

Large planetary imaging setups may, on occasion, pick up vague detail within the planet’s atmosphere, including banding and large-scale storms.

Being the most distant of the main planets, Neptune doesn’t give up its secrets easily, but amazingly its largest moon, Triton, can be seen quite easily through a 200mm instrument. Triton shines at mag. +13.5.

Observing the planets in October 2022

Neptune

• Best time to see: 1 October, 23:00 UT
• Altitude: 33º
• Location: Aquarius
• Direction: South
• Features: Colour, occasional atmospheric effects, Triton
• Recommended equipment: 200mm or larger

Mercury

• Best time to see: 8 October, 30 minutes before sunrise
• Altitude: 12˚
• Location: Virgo
• Direction: East

A morning planet on 1 October, mag. +1.4 Mercury rises 70 minutes before the Sun. It improves markedly and by 8 October at mag. –0.2, reaches greatest western elongation, rising 100 minutes before sunrise. It remains well-placed to around 20 October, at mag. –0.9.

It remains bright, but its rising offset from the Sun then reduces. On 24 October, mag. –1.0 Mercury, preceded by a 1%-lit Moon, rises an hour before the Sun. By the end of the month, the rise time offset decreases to just 30 minutes.

Venus

• Best time to see: 1 October, 20 minutes before sunrise
• Altitude: 2˚ (extremely low)
• Location: Virgo
• Direction: East

Rising just 40 minutes before the Sun on 1 October, mag. –3.8 Venus is now becoming hard to see. Venus reaches superior conjunction on 22 October, thereafter re-emerging into the evening sky.

Mars

• Best time to see: 31 October, 03:00 UT
• Altitude: 61˚
• Location: Taurus
• Direction: South

Mars is now a major planet in the late evening to early morning sky. Rising in the northeast around 20:30 UT on 1 October, it reaches 60˚ as dawn breaks. Shining at mag. –0.6 on this date, it presents an apparent disc size of 11 arcseconds.

Passing just over 1˚ north of the Crab Nebula, M1, mid-month, Mars is joined by a 73%-lit Moon 3˚ to the north on 15 October. As the month ends, Mars shines at mag. –1.2 and is 15 arcseconds across.

Jupiter

• Best time to see: 1 October, 23:40 UT
• Altitude: 37˚
• Location: Pisces
• Direction: South

Following opposition, Jupiter remains superbly positioned. On 1 October, it shines at mag. –2.8, east and slightly south of the Circlet asterism in Pisces. On 8 October, it is joined by an almost full Moon less than 3˚ to the south as they rise.

By 31 October, it appears at mag. –2.7 and reaches its highest position in the sky, due south at 21:30 UT, at an altitude of 35˚ from the centre of the UK.

Saturn

• Best time to see: 1 October, 21:00 UT
• Altitude: 21˚
• Location: Capricornus
• Direction: South

At mag. +0.6 on 1 October, dimming to mag. +0.8 by the end of the month, Saturn reaches its highest position due south, under dark sky conditions all month, reaching 20˚ altitude as seen from the centre of the UK. A bright 81%-lit Moon lies nearby on the evening of 5 October.

Uranus

• Best time to see: 31 October, 00:30 UT
• Altitude: 53˚
• Location: Aries
• Direction: South

Uranus is extremely well-placed for UK viewing, appearing over 50˚ up when due south, from the centre of the UK. A 94%-lit waning gibbous Moon lies 2.5˚ west at 01:50 UT on 12 October.

This guide originally appeared in the October 2022 issue of BBC Sky at Night Magazine.