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Tales of two autumn comets: 88P Howell and M3 ATLAS

Two more comets – 88P Howell and M3 ATLAS – are worth exploring the skies by November 2020.

If you're like us, you've used every clear night during quarantine to get out and watch the night sky. Fortunately, 2020 has been a "comet year" so far with a steady stream of binocular comets, led by the bright comet C / 2020 F3 NEOWISE this summer. In autumn the number of comets rises again to +10. Comet C / 2020 P1 NEOWISE appears briefly at dawn at the end of October, and now two more comets adorn the morning and evening sky.

Comet 88P / Howell comes first. This is a periodic comet in a 5.5 year orbit. Comet 88P Howell last passed perihelion on September 26th. The comet passed 1.1 Astronomical Units (AU) from Earth on May 9, 2020, and this year Earth is racing in its orbit in front of the comet near the comet's five-year perihelion passage.

The orbit of Comet 88P Howell. Photo credit: NASA / JPL

Comet 88P Howell was discovered on the night of August 29, 1981 by astronomer Ellen Howell of the Palomar Observatory and is 0.35 AU out of orbit. In June 2042, it is closest to the first half of the 21st century at 0.76 AU.

88P Howell in 2020

In late October, the comet is well positioned about an hour after sunset at dusk, 20 degrees above the southwestern horizon for observers at mid-north latitude. Through the constellation of Sagittarius, the centaur turned archer, and past the evening planets of Jupiter and Saturn, southern viewers get the best view of 88P Howell high in the sky. The comet seems to stay steadily in place from one night to the next through November to December, running parallel to the ecliptic as it tries to catch up with fast Earth. This near-stationary apparent motion is due to the fact that we are walking straight away from the comet in November.

Comet 88P Howell from its 2015 apparition. Photo credit: Marion Haligowski-Radical Retinoscopy / iTelescope.

Fun fact: NASA's proposed Comet Rendezvous, Sample Acquisition, Examination and Return (CORSAIR) mission would have sent a spacecraft to visit Comet 88P Howell in 2024 to conduct a sample return in the early 2030s. CORSAIR lost the dragonfly mission to Titan.

Comet 88P Howell's twilight path through 2020. Photo credit: Starry Night.

Here is a list of sky dates with fate for Comet 88P / Howell in 2020:

October

(Note: Unless otherwise stated, all rounds have a conclusion.)

26-Passed 3 degrees from the globular cluster Messier 28.

31 passes only 3 arc minutes from the Phi Sagittarii star, +3.2 magnitude.

November

May 1st top at + 8th magnitude

2 passes near the star Nunki (Sigma Sagittarii) of magnitude +2.1.

5 passes near the star Tau Sagittarii of magnitude +3.3.

12- passes near the star +4.6 magnitude 52 Sagittarii.

13- passes within 4 degrees of Jupiter.

18- passes within 4 degrees of Saturn.

22 crosses in the astronomical constellation of Capricornus the sea goat.

December

19 passes near strength +3.7 star Nashira (Gamma Capricorni).

21 passes near the star +2.8 magnitude Deneb Algiedi (Delta Capricorni).

26- Cross the astronomical constellation of the water carrier Aquarius.

28- passes near the star Iota Aquarii of magnitude +4.3.

Comet 88P / Howell's heavenly path by the end of 2020. Photo credit: Starry Night.

January 2021

May 1st falls back below + 10th magnitude.

After that, we'll say goodbye to Comet 88P Howell for another five years until it comes out in 2025-2026.

Next up is comet C / 2020 M3 ATLAS, which was discovered on June 27, 2020 in the survey on the asteroid warning system for terrestrial impacts.

In a 139-year orbit, comet M3 ATLAS went unnoticed during its last passage in late 1881.

At the end of October 2020, the comet will migrate locally to the south around 4 a.m., which makes it well suited for observations before sunrise. The comet also visits the star-studded realm of Orion, another plus. By the end of November, the comet is moving locally at 2 a.m. at 80 degrees above the southern horizon, viewed from 30 degrees north latitude.

The local path of comet M3 ATLAS at 4am through October to November 2020. Photo credit: Starry Night.

On its closest approach in mid-November, comet M3 ATLAS moves at around 2 degrees per day or a period of 4 full moons.

"My visual estimate on October 18 was a magnitude of +7.8 with 15 x 70 mm binoculars," veteran comet observer Michael Mattiazzo told Universe Today. “The comet had a large coma 15 feet in diameter, but it was quite diffuse. Dark sky is required to see it. Although the comet rises in the east in the evening, it is better located in the morning sky in the constellation Lepus. In the first week of November, when in Orion, it should reach +7.0 size with a 20 'coma. "

Here is the data to look out for from the M3 ATLAS when you get near you:

October

21 passes near the star Epsilon Leporis of magnitude +3.2.

26-Reaches perihelion at 1.269 AU from the sun.

27-Passes 10 ’from the star Mu Leporis with a strength of +3.3.

The light curve for Comet C / 2020 M3 ATLAS. Adapted from Seiichi Yoshida's weekly information on bright comets.

November

2 crosses in the constellation Orion the hunter.

3 pass 1.5 degrees from the bright star Rigel.

5- Passes near the star Tau Orionis of magnitude +3.6.

6- Passed 3 degrees from the Great Orion Nebula, Messier 42.

11- Cross the celestial equator to the north.

14 passes closest to Earth and 0.358 AU away.

15- passes near the star Bellatrix.

23 passes into the astronomical constellation of Taurus the Taurus.

27- Photo-op: Passed 2 degrees from the Crab Nebula, Messier 1.

29-Cross the ecliptic plane to the north.

The heavenly path of comet M3 ATLAS by the end of 2020. Photo credit: Starry Night.

December

May 1st falls back below + 10th magnitude.

The comet actually reaches a resistance of 180 degrees to the sun on December 13th. We can then say goodbye to comet M3 ATLAS until it returns to the inner solar system around AD 2159 in the middle of the next century.

Our preferred mode for finding comets is to simply use binoculars and scan the suspicious field for a blurry "star" that looks like a globular cluster that stubbornly refuses to focus. Observe a comet for several hours and you may see its slight orbital motion against the starry background. The passages near bright stars listed above are particularly useful as celestial delineators to help you find the respective comet.

… And 2020 has at least one more bright comet in store: C / 2020 S3 Erasmus, which is supposed to brighten up to 6th strength in mid-November. More will follow in the next month.

Don't miss the Comets Fall Parade, which surpasses astronomy in 2020.

Photo credit: Comet M3 Atlas dated October 18. Picture credits and copyright: Michael Mattiazzo.

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