Comet C/2020 S3 (Erasmus) will make its closest approach to the Earth on 17 November, at a distance of of 1.04 AU.

The comet's perigee – closest approach to Earth – should not be confused with its perihelion, when it passes closest to the Sun. Comets become much brighter when they pass close to the Sun. At perihelion their surfaces are heated and produce clouds of dust which give rise to their tails and extended coma around the nucleus. As a result, most comets are brightest around the time of their perihelion, not their perigee.

From Cambridge on the day of perigee it will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 15° above the horizon at dawn.

The events that comprise the 2020–2021 apparition of C/2020 S3 (Erasmus) are as follows:

The table below lists the times when C/2020 S3 (Erasmus) will be visible from Cambridge day-by-day through its apparition:

A more detailed table of C/2020 S3 (Erasmus)'s position on each night is available here. A diagram of the orbit of C/2020 S3 (Erasmus) is available here.

Finder chart

The chart below shows the path of C/2020 S3 (Erasmus) over the course of its apparition, as calculated from the orbital elements published by the Minor Planet Center (MPC). It is available for download, either on dark background, in PNG, PDF or SVG formats, or on a light background, in PNG, PDF or SVG formats. It was produced using StarCharter.

Click to expand »

Comet brightnesses

Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet's coma and tail. This dust is continually streaming away from the comet's nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet's nucleus, as it is heated by the Sun's rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.

In consequence, while the future positions of comets are usually known with a high degree of confidence, their future brightnesses are not. For most comets, we do not publish any magnitude estimates at all. For the few comets where we do make estimates, we generally prefer the BAA's magnitude parameters to those published by the Minor Planet Center, since they are typically updated more often.

No estimate for the brightness of comet C/2020 S3 (Erasmus) is currently available.

The comet's position at perigee will be:

The coordinates are given in J2000.0.

The sky on 17 Nov 2020

Source

This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC) , and is updated whenever new elements become available. It was last updated on 10 Dec 2024.

Image credit

© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.

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