Comets to look for in the spring night sky

As March opens, there are a number of comets visible to observers with binoculars and small telescopes. Finding them will be a fun challenge as none of them is easy to spot.

Comet Johnson
Stuart Atkinson, director of the SPA Comet Section, took this image of Comet Johnson from Cumbria on February 28, using a Canon 1100D fitted with a 300mm lens. Image credit: Stuart Atkinson

As the sky darkens, northern hemisphere observers can look out for Comet 2P/Encke, which is one of the regular visitors to our skies, with an orbit around the Sun lasting just 3.3 years.

In the first week of March you can find the comet low in the western sky as it heads towards perihelion, its closest approach to the Sun. With transparent skies and an unobstructed horizon, it is expected to shine at around sixth magnitude. Our chart shows its positions from mid-northern latitudes before it sinks too low in the twilight.

positions for Comet 2P/Encke
This chart shows positions for Comet 2P/Encke in the evening sky in early March 2017. The dates are given in the format “month-day”. Click to enlarge. Chart by Skymania, using Cartes du Ciel

An easier way you can see Comet Encke will be to keep an eye on images from Sun-watching satellite SOHO. The comet will pass through the field of its C3 camera in late March when it might have reached 3rd magnitude.

Incidentally, Comet Encke has the catalogue number 2P because it was the second of these celestial nomads to be recognised as a regular, or periodic, visitor. The first was the famous Halley’s Comet, which is known as Comet 1P/Halley.

Other comets visible are currently fainter than Encke but may be easier to observe directly as they can be seen higher up against a darker sky.

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We reported earlier on the show being put on by Comet 45P/Honda-Mrkos-Pajdusakova as it passed relatively close to the Earth. Now receding into space again, the comet is fast fading. However, its fuzzy but condensed coma was easily visible during February in typical astronomical binoculars, such as 10×50 models.

Comet 48P/Johnson
The track of Comet 48P/Johnson across the sky over the coming weeks. The dates are given in the format “month-day”. Click to enlarge. Chart by Skymania using Cartes du Ciel

As Comet 45P fades, another is steadily brightening and you can find it rising in the east during the later hours of the night. Comet 48P/Johnson moves slowly across Virgo during March and is currently around 10th magnitude, but is expected to become a bright binocular by the summer.

Also brightening as it crosses a dark sky is Comet 41P/Tuttle-Giacobini-Kresak. It was expected to be at magnitude 9 in the first week of March but should become a magnitude or two brighter during April.

Remember that all comets are unpredictable and so may be fainter than expected or even occasionally flare in brightness. Being fuzzy in nature, they are easy to distinguish against the stars but bright moonlight will make them harder to see.

You can experiment with a camera to try to capture an image, providing you can take a time exposure lasting more than a few seconds. Follow our advice in this previous post about photographing bright asteroid Vesta.

Comet 41P/Tuttle-Giacobini-Kresak
Comet 41P/Tuttle-Giacobini-Kresak’s path across the sky during March and April. The dates are given in the format “month-day”. Click to enlarge. Chart by Skymania using Cartes du Ciel

By Paul Sutherland

Paul Sutherland has been a professional journalist for nearly 40 years. He writes regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy, plus he has authored three books on astronomy and contributed to others.

2 thoughts on “Comets to look for in the spring night sky

  • 03/02/2017 at 1:15 am

    I just saw a comet in Washingtonville ny,March 1,2017 at 8 p.m. I saw it without a telescope,it is currently west of Washingtonville North-west of our moon.

  • 03/02/2017 at 7:36 am

    There are no comets visible with the naked eye at the moment. However, the Moon did pass close to planet Mars last night.

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