Comet Neowise
July 2020

by Roger Davies

C omet Neowise is now a beautiful sight just above the northern horizon and is expected to be visible throughout July and perhaps into August. It is possibly the most dramatic comet since Hale-Bopp in 1997.

The opening picture above is reproduced from here. There is further commentary directly from the National Aeronautics and Space Administration Centre (NASA) including more photographs posted by NASA here.

The comet was discovered in March by NASA's Near-Earth Object Wide-field Infrared Survey (thus the name). It will come closest to the Earth on July 23 when it will be 64 million miles away. This comet has come in from the outer reaches of the Solar System. Its nucleus, which is about 5km across, is made from dark organic materials that astronomers call 'dust' held together by frozen water and carbon dioxide with perhaps some ammonia, carbon monoxide and methane. It may have a small rocky core. As the comet approaches the Sun it heats up and the ices melt releasing the material that forms the tail which reflects the Sun's light. Comet tails always point away from the Sun.

You need a clear view to the northern horizon to see it. It is approximately due north at midnight on 13th July but only about 5 degrees above the horizon. It is visible with the naked eye, and with binoculars it's quite spectacular.

Comet Neowise captured from Hengistbury Head, Dorset. Photograph by Jim Maclannan; you can view its original plus some additional pictures here.

Above, Comet Neowise photographed over Headington, Oxford, by Professor Pat Roche.

Throughout July the comet will move west in the sky reaching Ursa Major — the Great Bear or Plough — by the end of the month.

The diagram below shows how Neowise moves across the sky in July. As the month proceeds the Sun sets earlier, the sky gets dark earlier, and it will be possible to see Neowise earlier in the evening. It is easiest to see when there is no Moon. New Moon is July 20th so the few days around then are likely to give the best view.

Through July the comet will move west in the sky reaching Ursa Major by the end of the month. This diagram is from the Royal Astronomical Society. Image credit with thanks to Stuart Atkinson, and you can enlarge the original image here.

SEE ALSO by Roger Davies:
Stargazing • February 2021
Stargazing • November 2020
Stargazing • September 2020
Comet Neowise • July 2020
Stargazing • July & August 2020
Stargazing • June 2020
Stargazing • May 2020
Stargazing • April 2020

Roger Davies is a resident of the village of Kidlington, Oxfordshire.

Roger is the Philip Wetton Professor of Astrophysics and Director of the Hintze Centre for Astrophysical Surveys at the Department of Physics, University of Oxford,

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