How to see the planets in the night sky, February 2021

February 2021 presents a last-chance opportunity to grab a view of Uranus before it’s engulfed by the evening twilight, not to return to UK dark skies until next autumn.

This is because Uranus is now losing altitude as true darkness falls, the evening twilight rapidly expanding to encompass the planet.

Yet, the ice giant still manages a healthy altitude of 46˚ from the centre of the UK in darkness at the start of February 2021, a figure that drops to 30˚ by the end of the month.

Despite having a diameter of 50,700km, at its great distance of 19.9 AU Uranus presents a tiny disc, just 3.5 arcseconds across.

Find out what’s happening throughout the rest of the year in our guide to observing the planets in 2021.

This is about three times the apparent diameter of Jupiter’s largest moon Ganymede as it appears from Earth.

There’s not a lot of detail visible on Uranus’s tiny disc. Larger instruments or high-resolution planetary imaging setups may show atmospheric banding, especially through long-pass red filters.

Rare, bright storms do occur in Uranus’s atmosphere and if  these are particularly large, they may be detected and recorded  by amateur equipment.

Sitting on the threshold of naked-eye visibility at mag. +5.8 (for more on this, read our guide on how to see Uranus with the naked eye), Uranus is best detected with a bit of optical assistance, such as that given by binoculars.

However, through such a small instrument the planet simply appears like a sixth magnitude star.

A small telescope will reveal the planet’s green hue, something that is
quite striking if you’ve never seen it before.

A 31%-lit Moon passes 3.2˚ south of Uranus on the evening of 17 February, presenting a good opportunity for catching both objects in the same photographic field of view with, say, a DSLR camera and a 300mm lens.

For more on this, read our guide on how to take photos of Uranus and Neptune.

How to see the planets in February 2021

Uranus

• Best time to see 1 February, 18:50 UT
• Altitude 48˚
• Location Aries
• Direction Southwest
• Features Colour, moons, subtle banded atmosphere
• Recommended equipment 150mm or larger

Mercury

• Best time to see 1 February, from 40 minutes after sunset
• Altitude 5˚ (low)
• Location Aquarius
• Direction West-southwest

Mercury is best seen at the start of February when it’s visible in the evening sky, setting 70 minutes after the Sun on 1 February. At mag. +1.4, it’s not very bright, which will hamper attempts to locate it.

It then heads towards the Sun, probably becoming lost from view on 5 February, while inferior conjunction occurs on 8 February. After this Mercury emerges again into the morning sky, passing close to Jupiter and Saturn over February’s last half.

Venus

• Best time to see 1 February, 20 minutes before sunrise
• Altitude 0.5˚ (extremely low)
• Location Sagittarius
• Direction Southeast

Mag. –3.9 Venus is a morning object, poorly positioned due to a shallow ecliptic angle. The time between Venus rising and sunrise reduces from 26 minutes at the start of February to zero at the month’s end.

Venus and Jupiter are 31 arcminutes apart on 11 February which will be tricky to spot in the morning twilight as Venus rises just 12 minutes before the Sun.

Mars

• Best time to see 1 February, 18:30 UT
• Altitude 54˚
• Location Aries
• Direction Just west of south

Mars fades this month, from mag. +0.4 on the 1st to +0.9 by its close. Through a scope the planet shows an 89% disc during February, its apparent size dipping from 7.9 to 6.4 arcseconds over the month.

A 40%-lit waxing crescent Moon sits 5˚ from Mars on the evening of 18 February. By the end of the month, Mars will sit 3.3˚ south of the Pleiades.

Jupiter

• Best time to see 28 February, 20 minutes before sunrise
• Altitude 1.3˚ (very low)
• Location Capricornus
• Direction Southeast

Jupiter and Saturn re-emerge from solar conjunction into the morning sky this month, but are too close to the Sun to be seen properly. A close conjunction between Jupiter and Venus occurs on the morning of 11 February, with both planets being half a degree apart.

They will be difficult to see though, rising 10 minutes before the Sun. By the 28th, Jupiter and Saturn are on view above a flat southeast horizon shortly before sunrise.

Saturn

• Best time to see 28 February, 30 minutes before sunrise
• Altitude 2˚ (very low)
• Location Capricornus
• Direction Southeast

Saturn was in conjunction with the Sun on 24 January and now appears in the morning sky. It’s poorly positioned all month. The best chance of spotting it will be on 28 February, when it rises one hour before the Sun.

Neptune

• Best time to see 1 February, 19:00 UT
• Altitude 11˚
• Location Aquarius
• Direction West-southwest

Neptune is a compromised evening planet, only achieving 11˚ altitude above the west-southwest horizon on the 1st under truly dark conditions. It requires binoculars to see, shining at mag. +8.0. By the end of February, it will be lost to the evening twilight glow.

Pete Lawrence is an experienced astronomer and a co-host on The Sky at Night. This article originally appeared in the February 2021 issue of BBC Sky at Night Magazine.