How and when to see the green comet from the US

A green comet is crossing the night sky. Discovered in March 2022, the comet scientifically named C/2022 E3 (ZTF) is a long-range traveler, whose elongated orbit describes an ellipse that extends to the Oort cloud, the region that marks the limits of the Solar System, where it wandered in total darkness for thousands of years, before gravitational pull propelled its journey back to the worlds closest to the Sun.

The path of comets to the inner Solar System involves leaving the icy darkness of the confines of our cosmic neighborhood and increasing their temperature as they approach the Sun. The heat then sublimates the surface ice and forms a gas cloud, or coma, that envelops the nucleus and above all, a characteristic tail that grows in the opposite direction to the Sun and can extend for tens of millions of kilometers.

The coma and the distinctive tail of comets have been key to their identification since the dawn of ancient civilizations, which tied their dramatic appearance in the sky with dire omens that warned of impending wars, droughts or famines. However, the long history of C/2022 E3 dates back to a period predating the expansion of Homo sapiens on Earth: about 50,000 years ago, when the green comet loomed in the skies of the hot and rocky worlds of the inner planets of the Solar System for the last time, Neanderthals were the dominant human species in Europe. Hence, the passage of C/2022 E3 is an unrepeatable event on a human scale.

When will the green comet be seen in the US?

On January 12, C/2022 E3 reached the closest point in its orbit to the Sun (perihelion). Since then, the distance between the comet and Earth has been reduced day by day and is making its closest approach (perigee) on February 1, when the two will be only 42 million kilometers apart, just over a hundred times the average distance between the Earth and the Moon (and a quarter of the distance that separates the Sun from our planet). The best time to see the green comet is from the weekend of January 28 and 29 until the night of February 2, when it will begin to move away definitively towards the confines of the Solar System.

How to locate the green comet in the night sky and at what time to observe it?

Comet C/2022 C3 will be visible to the naked eye in rural areas far from large cities and therefore free from light pollution. To find it, just look to the north and locate the Pole Star, the brightest of the Little Dipper.

The comet is visible from the northern hemisphere and on the night of its closest approach, on February 1, it will appear just above the North Star at around 11pm, an ideal time to look at it with binoculars or a telescope and capture its passage.

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