Night sky highlights - April 2018

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The best of astronomy this month: Look for the Moon beside Mars and Saturn in the early morning of 7th and 8th April.

By Dhara Patel, Astronomy Education Officer

(Details given are for London and may vary for other parts of the UK).

Top 3 things to see this month:

2nd Apr - Catch Mars and Saturn close together in the predawn sky.

1st -7th Apr - Spot the Moon pass by Spica, Jupiter, Saturn and Mars.

22nd-23rd Apr - Look out for the Lyrid metoer shower.

Look Up! Podcast

As well as taking you what to see in the night sky each month, Royal Observatory Greenwich astronomers pick their favourite astro news story. For April, they're talking about a zombie star - the observation of a star that has died and apparently come back to life again and also Jupiter's famous Great Red Spot - it's shrinking, growing taller and that's not all that the Juno spaceprobe has discovered about Jupiter's stormy surface! Have a listen below then vote for your favourite news story on our Twitter poll during the first week of the month.

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2 April

Saturn and Mars

Early on in the month, on the 2nd April, Mars makes a close approach with Saturn low in the pre-dawn sky. Look towards the south at about 6am for your best chance to see them when they are only about 1 degree apart, about the width of your little finger held at arm’s length. Mars, with its deep orange-red colour and Saturn make fantastic objects to see with the naked eye or a pair of binoculars. It’s even possible to make out the white frozen polar regions of Mars and the grand rings of Saturn with a small telescope. For a planet appearing at a more civilised time of the night, try looking to the west with the setting Sun to see the bright planet Venus, visible throughout April. 

Find out more interesting facts about Venus

1-8 April

Moon, Spica, Jupiter, Antares, Saturn, Mars

The Moon begins this month in its waning gibbous phase having just had a full moon on the last day of March. Appearing in the south-eastern sky after midnight, the first week of April will have it start by the bright star Spica in the constellation of Virgo, pass by Jupiter which will be in the constellation of Libra, then move past the brightest star in the constellation of Scorpius - Antares, before approaching Mars and Saturn by the 7th and 8th. While Spica is in reality a double star system, the two stars take only 4 days to circle one another, making them far too close together to be separable by even the largest telescopes.

21 April

Moon, Pollux and Castor

By the 21st of April, the Moon will be passing through the constellation of Gemini. Look towards the west in the early evening before midnight. Here the Moon passes by the bright stars Pollux and Castor, the twins. In Greek and Roman mythology, immortal Pollux shared his immortality with his mortal twin following Castor’s death, leading to them taking their place in the stars as the constellation of Gemini we see today. In reality, Pollux is an aging orange giant star slowly closing in on the end of its life while Castor is in fact six different stars, 3 sets of close binaries all combining to make the single point of light.

22-23 April

The Moon will reach its new moon phase on the 16th April, but will still be mostly out of the way for the first of two meteor showers that grace our skies this month. The Lyrid meteor shower will peak on the 22nd to 23rd April. While its expected rate of about 20 meteors per hour in ideal conditions is far from the greatest, the favourable observing conditions and possibility of persistent trains behind some of the meteors makes the Lyrids worth a watch. While the radiant of the meteor shower lies in the constellation of Lyra (visible in the east), the meteors can be seen all over the sky.

When watching meteor showers, try to find an open space with a low horizon and wait until the hours after midnight for your best chance to see them. Your local astronomy society may well be organising a meeting for the shower so be sure to check. Just remember to keep warm; it’s not summer just yet! While the Eta Aquariid meteor shower also begins to ramp up from the 19th April, it won’t actually peak until the first week of May.

29-30 April

Mercury (east), Moon and Jupiter (west)

Through much of April, Mercury is too close to the Sun to be visible, having been between the Earth and Sun on the 1st, a point known as the inferior conjunction of the planet. However by the 29th of April, the planet will have reached its greatest western elongation, placing it as far from the Sun as it will get from our viewpoint. However it will still only just peek above the eastern horizon before the Sun rises, drowning out our view. Finally this month, the Moon will reach its full moon phase in the early hours of 30th. It will re-join Jupiter in the south-eastern sky from around sunset on 29th and remain visible throughout the night until it sets in the west just after the Sun rises on 30th.

The Moon's phases this month

Evening in the Ptolemaeus Chain and Rupes Recta Region © Jordi Delpeix Borrell
Evening in the Ptolemaeus Chain and Rupes Recta Region © Jordi Delpeix Borrell
  • 8 Apr - last quarter moon (07:18am)
  • 16 Apr - new moon (01:57am)
  • 22 Apr - first quarter moon (09:46pm)
  • 30 Apr - full moon (00:58am)

See the other incredible photographs from the 2017 Insight Astronomy Photographer competition in our free exhibition like Evening in the Ptolemaeus and Rupes Recta Region by Jordi Delpeix Borrell which was the runner up for Our Moon category.

Stargazing tips

  • When looking at faint objects such as stars, nebulae, the Milky Way and other galaxies it is important to allow your eyes to adapt to the dark – so that you achieve night vision.
  • Allow 15 minutes for your eyes to become sensitive in the dark and remember not to look at your mobile phone or any other bright device when stargazing.
  • If you are using a star app on your phone switch on the red night vision mode.
  • Need a stargazing telescope or decent binoculars? Check out our range of high-quality observing equipment recommended by Royal Observatory astronomers:

See our range of observing equipment

Share your astronomy pictures

Congratulations to Ruslan Merzlyakov for his beautiful images of the night sky. He shared his image on our astrophotography Facebook page and we chose it for April's banner image.

If you want to be in with a chance to showcase your astrophotography skills on the banner of next month's night sky blog, share your photos via our Royal Observatory Astrophotography Facebook group

You can also connect with us on Twiiter @ROGAstronomers

Insight Astronomy Photographer of the Year

Encounter of Comet and Planetary Nebula © Gerald Rhemann
Encounter of Comet and Planetary Nebula © Gerald Rhemann

Come and see the brilliant entries and winner to the world's biggest astrophotography competition in our free exhibition at the Royal Observatory until July 2018.

See the 2017 Insight Astronomy Photographer of the Year competition

See more of the night sky

Come on amazing tour of this month's night sky in our SkyTonight planetarium show delivered live by a Royal Observatory Greenwich astronomer.

See the Sky Tonight planetarium show

Central image: © Ruslan Merzlyakov

Resources for teachers and students

The Royal Observatory learning team have also created:

  • Free animated videos that answer the biggest questions in astronomy and free resources to go alongside them. We've just released 3 brand new videos! 

You can find them here

ROG video 'Where does Space begin?'
ROG video 'Where does Space begin?'
  • A whole host of podcasts featuring interviews with real space scientists, astronauts and active researchers working in UK Universities.

You can listen to these here

Nimisha Kumari, Astronomer
Nimisha Kumari, Astronomer