Comet C/2021 T4 Lemmon: A Long-Period Visitor Sweeping the Southern Sky in 2023

Famous British astronomer Guy Otewell This article was originally published about Comet C/2021 T4 Lemon on May 25, 2023. Reprinted with permission. Edits by EarthSky.

Komet C/2021 T4 Lemon

Comet C/2021 T4 Lemmon was discovered on October 7, 2021, in this image taken at Lemon Mountain ObservatoryNortheast of Tucson, Arizona. T4 That would mean a fourth find or recovery in the first half of October.

Mount Limon is the highest point in the Santa Catalina Mountains, one of four mountains surrounding Tucson. Not to be confused with Catiline, the conspirators who attempted to seize power over the Roman Republic in 63 BC. I remember surmising that the Navajo may have seen Canopus, the great southern star, from one of the four sacred peaks that surround their land. In fact, it is featured as a cover photo Calendar astronomy 2023.

After its discovery, Comet C/2021 T4, due to its orbital geometry, appeared directly north, with an eccentricity of +12°.

Comet C/2021 T4 Lemon is a long-period comet

In fact, it’s a long-term offender; If it had previously fallen from its distant home – at 44,000 AU – into the inner solar system, it would have done so millions of years ago. So during its current travel, you will feel gravity disturbance One of the planets whose duration will be shortened to just thousands of years.

Its orbit is tilted about 20 degrees to the plane of the ecliptic. However, it is moving backwards, or against the direction of the planet’s rotation. The result is that it will make a very long and fast sweep across the southern sky.

Researcher scheme

Currently the comet is located 60 degrees in the morning sky, south (at a declination of -13 degrees), 1.75 astronomical units from the Sun and 2 astronomical units from Earth. However, it’s still a lackluster size around 11. Then, on June 27, 2023, our distance between us will shrink to 1 AU.

On July 18, 2023, we will authorize it. And around this time, it’s closest to us, 0.54 AU, and brightest, maybe 8 or 7, but still well below the naked eye limit. Its proximity would make it appear far to the south, at a declination of -56 degrees on July 20.

Then in the following months it will climb further north, becoming lower in the night sky and farther away. At the same time it will dim maybe 2 or 3. It will arrive the lowest1.48 AU from the Sun, on July 31, 2023. Finally, it will ascend through the ecliptic on September 10, 2023, and conjunction behind and north of the Sun on November 9, 2023.

Of course, we must remember that predictions about the comet’s brilliance and the size of its tail are unreliable. That’s because it relies on melting ice and emission of dust in this clump of rotating matter.

Comet Hale-Bopp can still be observed? Extraordinary!

By the way, Alan Hill He (Jay Otewell) informed us of this comet via a Facebook post on May 22nd. Alan is the discoverer of the large comet Hale-Bopp (C/1995 O1). And while it is more than 47 astronomical units away, it is the first of its kind in space Minor Planet Center List of currently observable comets, not because of their current size (around 20) but because it is the first non-periodic comet ever seen.

Bottom line: Comet C/2021 T4 Lemmon was discovered by the Mount Lemmon Observatory in 2021. It is currently sweeping the southern sky.