From Fireballs To Comets - An Exciting Astronomical Week

What an astronomical week we have had! From the fireball(bolide) seen streaking across our skies to the asteroid BU2023 which made one of the closest approaches by a known near-Earth object(NEO) ever recorded. And now we have the infamous Green Comet which can be observed gracing the firmaments.

Now in relation to the Green Comet If there is someone in Gibraltar who is an expert on these “dirty snowballs” is none other than Mrs. Ana Russo. Ana has, for many years, been the proficient comet member of the Gibraltar Astronomical Society in which she contributes regularly on the subject matter. Reading her material on COMET C/2022 E3 (ZTF), which you can appraise below, you will comprehend that we are given the exact details, and data, and not overhyped “fake” information about this particular comet. Unfortunately, in these day and age we also receive false information even on astronomical events.

The piece Mrs. Russo has written is a true account of what to expect and how to observe this comet. Hope you all enjoy it.

William Recagno


Gibraltar Astronomical Society.


By Ana Russo, Gibraltar Astronomical Society Comet Section

Now and again comets, which are essentially dirty ice balls originating from a region far beyond the orbit of Pluto in the Oort Cloud, travel across the solar system towards the sun. As they approach it, the frozen gases and dust start to evaporate, forming a coma and tail which are so characteristic of comets. At the moment, a so called ‘green’ comet is present in our night sky, but is this one really deserving of all the recent media attention and expectation surrounding it?

Every year it is normal to see comets in our skies for a short period of time. Most are very faint and need large instruments to be seen. On rare occasions, around every 10 to 20 years, a large and bright comet will appear enabling us to see it naked eye showing details of its colour, structure and splendid long curved dust tail. The spectacular colour photographs we see in magazines and online are taken with specialist equipment and processed to enhance the visual effect and fine detail. This is not representative of what is normally seen visually through binoculars or telescopes.

On this occasion, comet C/2022 E3 ZTF was discovered by the Zwicky Transient Facility on the 2 March 2022.  It is a long period comet which has taken 50,000 years to get to the inner regions of the solar system and which can now be seen in our skies. It will make its closest approach to Earth on 1 February 2023.

Astronomers are surprised at the media hype surrounding this so called  ‘rare green comet’.  There is nothing special or rare about this comet being green. A large majority of comets show a greenish colour both visually and photographically. This is due to its chemical composition where carbon and cyanogen interact with the solar wind, a stream of charged particles emitted from the sun, which are ionized to produce a green glow.

It is projected that in a week’s time, when at its nearest to Earth, it will brighten and perhaps be seen with the naked eye, but nobody should be under any illusion that it will be anything like Hale-Bopp, the Great comet of 1997. This one is very small and for now can only be seen with binoculars and telescopes if you know where to look. Predictions give an estimated magnitude of 5 for this comet which would make it approximately 17 times fainter than Hale-Bopp, the brightest comet in recent history with a magnitude of -1.8!

The comet can be located in the constellation Ursa Minor (the Little Bear) close to the Pole Star. Binoculars or telescopes will be needed to locate it. Realistically it will only be visible to those keen to astronomy who are used to observing the night sky.  It will be seen as from 9pm local time looking north from the 28 January 2023 onward. Every night it will get higher in the sky and will be visible all night long.

Comets are well known for being very unpredictable and no one can accurately say what will happen in the coming days. It might get brighter, in which case it may become a naked eye object, or not. We’ll just have to wait and see.