The “Neanderthal comet” is returning to visit us after 50,000 years: when and where to observe it



Credit: Dan Bartlett

There Neanderthal comet it is approaching the Earth and will (probably) also be visible to the naked eye, especially from February 1, 2023: an event that hasn’t happened for about 50,000 years!
It was discovered in early 2022, but it is possible that humans have already seen it a long time ago, when Neanderthals still walked the Earth. That’s why the comet C/2022 E3 (ZTF) she was dubbed by the various media “Neanderthal comet”. Of course that is not said 50,000 years agoat the time of the last passage of the comet, this was visible to the naked eye of our very distant ancestors, but it makes a certain impression to think that this little celestial pebble hasn’t passed around here for so long and that it won’t return until just as long!
The comet is rapidly approaching Earth: let’s find out where and when to observe it.

The discovery of the Neanderthal comet

The Zwicky Transient Facility is an automatic sky scanning project that uses a telescope in California to discover new transients, i.e. celestial objects that vary rapidly in brightness (such as supernovae) or in position (such as asteroids or, precisely, comets). It was this project that discovered comet C/2022 E3 (ZTF), the March 2, 2022. At the time it was located at 640 million km from us and was a very weak object.

The Samuel Oschin telescope at Monte Palomar, used by the Zwicky Transient Facility project (credit: Palomar Observatory/Caltech).

The orbit of the comet

Subsequent observations of the comet allowed astronomers to reconstruct its orbit. We have thus discovered that this little “ball of space ice” is advancing into the inner solar system, getting closer and closer to the Earth and of course to the Sun. And we know what comets are like: the closer they get to the Sun, the more active they become. Thus, over the last few months the comet has become increasingly bright, developing a green foliage it’s a double tail.

Comet C/2022 E3 (ZTF) observed on October 16, 2022 (credit: Dan Bartlett).

It is normal for a comet to have two tails: one dust tailwhich extends along the trajectory traveled by the comet, and a ion tail pointing away from the Sun. A notable feature of C/2022 E3 (ZTF) is that it has a very long periodequal to approx 50,000 years. The last time this comet passed our planet our species was still abundantly in the prehistory! In short, this is the first passage of this comet to be documented.

And for the same reason it will be the only opportunity we will have to see it: the next time you pass by here to observe it there will be our very distant descendants.

When to observe the Neanderthal comet

The January 12th C/2022 E3 (ZTF) will reach the perihelionthat is, the point of its orbit closest to the Sun, at a distance of 166 million km from our star. This is the time to expect it increased activity of the comet, which grows as the amount of light and heat arriving from the Sun increases. The most favorable moment to see it will instead be around February 1stthe date on which the comet will reach the point of closest proximity to the Earth to 42 million km from our planet.

Comets are famously very unpredictable objects: their activity and their behavior depend on many factors and forecasts must always be taken with benefit of the doubt. However, the fact that perihelion will arrive bodes well first of the maximum proximity to the Earth: in this way the comet will already be “nicely charged” when it passes near our planet!

Astronomers’ models suggest that C/2022 E3 (ZTF) could reach from January 24th bright enough to be seen with the naked eye in skies exceptionally dark. However, if you don’t have a pristine sky at your fingertips, the comet should still be visible even with the aid of good binoculars. In short, don’t expect a great comet like the historic one Hale-Bopp of 1997: C/2022 E3 (ZTF) will appear as a striking wad of green light. Unless, of course, you are equipped with a telescope, which will allow you to better distinguish the details of this celestial object. In any case, for a better result we recommend observation of course after moonset.

In February the comet will become less and less luminous, until it disappears completely from view a the end of March.

Where to see it

The path in the sky of comet C/2022 E3 (ZTF) in the period of maximum visibility (credit: Jim Hendrickson).

The comet is currently located in the constellation of Corona Borealis, so it is already visible in the skies of the northern hemisphere (including ours!). In the coming weeks it will get closer and closer to the Celestial North Pole: this means that it will adorn our sky for longer and longer. Indeed, since 20 th January to the February 5th the comet will even be circumpolari.e. visible for all night long!
The January 22nd will move to the constellation ofUrsa Minor and from January 29th it will instead transit in the constellation of Giraffe. In February it will be the turn of the constellations ofCharioteer and then del Bull (with a transit on February 15 near the orange giant Aldebaran), to then touch the constellation of on the west side Orion until it disappears completely west of the supergiant star Regel.

Hurry Up!


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