APOD: The Further Tail of Comet Leonard (2021 Dec 30)

[APOD Robot]

The Further Tail of Comet Leonard

Explanation: Comet Leonard, brightest comet of 2021, is at the lower left of these two panels captured on December 29 in dark Atacama desert skies. Heading for its perihelion on January 3 Comet Leonard's visible tail has grown. Stacked exposures with a wide angle lens (also displayed in a reversed B/W scheme for contrast), trace the complicated ion tail for an amazing 60 degrees, with bright Jupiter shining near the horizon at lower right. Material vaporizing from Comet Leonard's nucleus, a mass of dust, rock, and ices about 1 kilometer across, has produced the long tail of ionized gas fluorescing in the sunlight. Likely flares on the comet's nucleus and buffeting by magnetic fields and the solar wind in recent weeks have resulted in the tail's irregular pinched and twisted appearance. Still days from its closest approach to the Sun, Comet Leonard's activity should continue. The comet is south of the Solar System's ecliptic plane as it sweeps through the southern constellation Microscopium.

<< Previous APOD

This Day in APOD

Next APOD >>

[Holger Nielsen]

Using Starry Night I have identified the bright object to the right as Jupiter and the bright star just right of the comet's tail as Fomalhaut.

[Ann]

Using Starry Night I have identified the bright object to the right as Jupiter and the bright star just right of the comet's tail as Fomalhaut.

Thanks, Holger! I was wondering!


Thanks to Holger, I have annotated a few more stars:

Sigma1 and Sigma2 Gruis make up the very blue-looking splotch in the upper left part of the APOD. They are a pair of A-type stars.


Ann

[Lasse H]

What is the sharp line doing -- to the left of the tail, visible as a black line in the negative?

[XgeoX]

What is the sharp line doing -- to the left of the tail, visible as a black line in the negative?

That’s a line added to show that the comet’s tail is 60 degrees long.

[orin stepanek]

The Comet Leonard must have a large amount of moisture and dust
to be shedding ihat long of a vapor trail! IMO

[Lasse H]

Thanx, XgeoX!

[ThoughtfulStarGazer]

These two wonderful image mosaics made me think about the motion of a comet nucleus and what might be happening and why. It looks to me like the nucleus is traveling in a spiral, like a thrown football,and the tail is its "wake."

The caption suggests:

"Likely flares on the comet's nucleus and buffeting by magnetic fields and the solar wind in recent weeks have resulted in the tail's irregular pinched and twisted appearance."

Could not an alternative be that the nucleus is rotating at a slow rate as a general result of traveling through space. Even though outer space is pretty empty, the matter which is there applies resistance to the nucleus, and over time a nucleus rotation would develop in a manner similar to what happens with extension cords coiled in loops? Although there would be no nucleus unwinding or spiral resistance because the comet is not tethered.

Thes images are the first I have seen of a comet's tail across such a long stretch of sky.

[Joe Stieber]

The second magnitude star Diphda (Beta Ceti or Deneb Kaitos) is also visible to the right of the tail's upper end. Roughly 8° below Diphda, a vague spot of haze marks the position of Comet 19P/Borrelly, as shown in this labeled crop of the positive APOD image. I happen to be aware of this because I was looking at 19P this past Sunday evening (Dec 26) at the end of astronomical twilight, subsequent to observing Comet Leonard a little earlier in twilight. Here at 40°N latitude, Leonard wasn't that far above the horizon after sunset, and it was just a small fuzzy patch in my 88 mm spotting scope. Borrelly was barely visible in that scope.
 

[Fred the Cat]

These two wonderful image mosaics made me think about the motion of a comet nucleus and what might be happening and why. It looks to me like the nucleus is traveling in a spiral, like a thrown football,and the tail is its "wake."

The caption suggests:

"Likely flares on the comet's nucleus and buffeting by magnetic fields and the solar wind in recent weeks have resulted in the tail's irregular pinched and twisted appearance."

Could not an alternative be that the nucleus is rotating at a slow rate as a general result of traveling through space. Even though outer space is pretty empty, the matter which is there applies resistance to the nucleus, and over time a nucleus rotation would develop in a manner similar to what happens with extension cords coiled in loops? Although there would be no nucleus unwinding or spiral resistance because the comet is not tethered.

Thes images are the first I have seen of a comet's tail across such a long stretch of sky.

Your post made me curious.

[neufer]

These two wonderful image mosaics made me think about the motion of a comet nucleus and what might be happening and why. It looks to me like the nucleus is traveling in a spiral, like a thrown football,and the tail is its "wake." The caption suggests: "Likely flares on the comet's nucleus and buffeting by magnetic fields and the solar wind in recent weeks have resulted in the tail's irregular pinched and twisted appearance."

Your post made me curious.

<<Scylla was loved by Glaucus, but Glaucus himself was also loved by the goddess sorceress Circe. While Scylla was bathing in the sea, the jealous Circe poured a baleful potion into the sea water which caused Scylla to transform into a frightful monster with four eyes and six long snaky necks equipped with grisly heads, each of which contained three rows of sharp shark's teeth. Her body consisted of 12 tentacle-like legs and a cat's tail, while six dog's heads ringed her waist. In Homer's Odyssey XII, Odysseus (i.e., Ulysses) is advised by Circe to sail closer to Scylla, for Charybdis could drown his whole ship: "Hug Scylla's crag—sail on past her—top speed! Better by far to lose six men and keep your ship than lose your entire crew.">>

Scylla as a maiden with a kētos tail and dog heads sprouting from her body.

---

<<The Ulysses spacecraft made an unexpected pass through the tail of Comet Hyakutake on 1 May 1996. Evidence of the encounter was not noticed until 1998. Astronomers analysing old data found that Ulysses' instruments had detected a large drop in the number of protons passing, as well as a change in the direction and strength of the local magnetic field. This implied that the spacecraft had crossed the 'wake' of an object, most likely a comet; the object responsible was not immediately identified.

In 2000, two teams independently analyzed the same event. The magnetometer team realized that the changes in the direction of the magnetic field mentioned above agreed with the "draping" pattern expected in a comet's ion, or plasma tail. The magnetometer team looked for likely suspects. No known comets were located near the satellite, but looking further afield, they found that Hyakutake, 500 million km (3.3 AU) away, had crossed Ulysses' orbital plane on 23 April 1996. The solar wind had a velocity at the time of about 750 km/s, at which speed it would have taken eight days for the tail to be carried out to where the spacecraft was situated at 3.73 AU, approximately 45 degrees out of the ecliptic plane. The orientation of the ion tail inferred from the magnetic field measurements agreed with the source lying in Comet Hyakutake's orbital plane.

The other team, working on data from the spacecraft's ion composition spectrometer, discovered a sudden large spike in detected levels of ionised particles at the same time. The relative abundances of chemical elements detected indicated that the object responsible was definitely a comet.

Based on the Ulysses encounter, the comet's tail is known to have been at least 570 million km (360 million miles; 3.8 AU) long. This is almost twice as long as the previous longest-known cometary tail, that of the Great Comet of 1843, which was 2.2 AU long.>>