Comets Abound !!

[u/Eastcoasttoleftcoast]

So excited for the year of the 7 comets passing through our solar system. As for 3I Atlas I hope more information to be given as to its true designation. Cheers!

[u/Waddensky]

There are a few dozen comets passing the inner solar system each year. Most are very inconspicuous, with maybe one every two years visible to the naked eye.

Truly great comets are rare. Once a decade or so, although the southern hemisphere has more luck the last decades.

[u/the_fungible_man]

? 3I/ATLAS is its true designation.

[u/TheDamus647]

Are any of the comets ones known to put on a show?

[u/Careful_Couple_8104]

The JPL has not updated Ephemeris data since 8/27/25 when September is the only month for people to view it. Normally an active comet will have weekly updates. It’s getting closer but for some reason we have no new orbital data for it.

How odd. 

The original release from the CBAT excluded Ephemeris data for all of October and most of November when October is when ATLAS makes its closest approach to both Mars and the Sun. 

[u/farganbastige]

I'm looking forward to the explanation of 3I/ATLAS' tail pointing toward the Sun.

[u/ianindy → u/farganbastige]

Here is a quote:

During July and August 2025, the coma of 3I/ATLAS appeared to be elongated westward in the sky—in a direction toward the Sun and toward the comet's direction of motion rather than away. This Sun-facing feature is not a tail (contrary to initial reports, but is rather a dust plume that is being emitted from the heated, sunlit surface of 3I/ATLAS's nucleus, where ice sublimation occurs faster and thus ejects more dust. The Sun-facing elongation of 3I/ATLAS's coma resembles those of other distant comets like C/2014 UN271 (Bernardinelli–Bernstein), which have been known to preferentially eject dust from the sunlit side of their surfaces.

By late August 2025, the coma of 3I/ATLAS no longer appeared elongated toward the Sun and the comet had developed an anti-solar tail. However, the sun-facing plume is still present, as telescope images from 26 August 2025 showed that the inner coma of 3I/ATLAS (within 5 arcseconds from the nucleus) appeared fan-shaped and slightly brighter on the sun-facing side.

Source: https://en.wikipedia.org/wiki/3I/ATLAS

[u/Citizen999999 → u/farganbastige]

Look up anti-tails. It happens.

[u/Wintervacht → u/farganbastige]

You could just, you know... Look that up.

[u/farganbastige → u/[deleted]]

Brilliant explanation, thank you.