Tales of Two Fall Comets: 88P Howell and M3 ATLAS

Two more comets – 88P Howell and M3 ATLAS – are worth scouting the sky for into November 2020.

If you’re like us, you’ve been at taking advantage of every clear night during quarantine to get out and observe the night sky. Thankfully, 2020 has thus far been a ‘comet year,’ with a steady string of binocular comets, led by bright comet C/2020 F3 NEOWISE this summer. Fall is seeing another surge in comets topping +10^th magnitude. Late October sees a brief dawn apparition of Comet C/2020 P1 NEOWISE and now, two other comets grace the dawn and dusk skies.

First up is Comet 88P/Howell. This is a periodic comet, on a 5.5 year orbit. Comet 88P Howell last passed perihelion on September 26^th. The comet passed 1.1 Astronomical Units (AU) from the Earth on May 9^th, 2020, and this year sees the Earth racing ahead of the comet in its orbit, near the comet’s quinquennial perihelion passage.

Discovered by astronomer Ellen Howell from Palomar Observatory on the night of August 29^th, 1981, Comet 88P Howell crosses 0.35 AU exterior to the orbit of the Earth, and makes its closest pass for the first half of the 21^st century of 0.76 AU in June 2042.

88P Howell in 2020

Late October sees the comet well-placed at dusk about an hour after sunset, 20 degrees above the southwest horizon for mid-northern latitude observers. Crossing through the constellation of Sagittarius the Centaur-turned-Archer and past the evening planets of Jupiter and Saturn, southern viewers get the very best view of 88P Howell high in the sky. The comet seems to hold steadily in place from one night to the next through November into December, running parallel to the ecliptic as it attempts to play catch-up with the speedy Earth. This near-stationary apparent motion is because we are moving directly away from the comet in November.

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

Here’s a list of celestial dates with destiny for Comet 88P/Howell in 2020:

October

(Note: all passes are with one degree unless otherwise noted)

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

31-Passes just 3 arcminutes from the +3.2 magnitude star Phi Sagittarii.

November

1-May top out at +8^th magnitude

2-Passes near the +2.1 magnitude star Nunki (Sigma Sagittarii).

5-Passes near the +3.3 magnitude star Tau Sagittarii.

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

13- Passes within 4 degrees of Jupiter.

18- Passes within 4 degrees of Saturn.

22-Crosses into the astronomical constellation of Capricornus the Sea Goat.

December

19-Passes near the magnitude +3.7 star Nashira (Gamma Capricorni).

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

26- Crosses into the astronomical constellation of Aquarius the water-bearer.

28- Passes near the +4.3 magnitude star Iota Aquarii.

January 2021

1-May drop back down below +10^th magnitude.

After that, we say goodbye to Comet 88P Howell for another 5-odd years, until its 2025-2026 apparition.

Next up is Comet C/2020 M3 ATLAS this was discovered by the Asteroid terrestrial Impact Last Alert System survey on June 27^th, 2020.

On a 139 year orbit, comet M3 ATLAS went unnoticed on its last passage in late 1881.

In 2020, late October sees the comet transiting to the south around 4 AM local, making it well placed for pre-dawn observations. The comet also visits the star-dappled realm of Orion, another plus. By late November, the comet is transiting at 2AM local at 80 degrees above the southern horizon as seen from latitude 30 degrees north.

At its closest approach in mid-November, Comet M3 ATLAS will be moving at about 2 degrees per day, or the span of 4 Full Moons.

“My visual estimate on Oct 18th was magnitude +7.8 using 15x70mm binoculars,” veteran comet observer Michael Mattiazzo told Universe Today. “The comet sported a big coma, 15′ across, but quite diffuse. Dark skies are required to see it. Although the comet rises in the east during the evening, it is better situated in the morning sky in the constellation of Lepus. In the first week of November, when situated in Orion, it should reach magnitude +7.0 with a 20′ coma.”

Here’s dates to watch for from M3 ATLAS, coming to a sky near you:

October

21-Passes near +3.2 magnitude star Epsilon Leporis.

26-Reaches perihelion, at 1.269 AU from the Sun.

27-Passes 10’ from +3.3 magnitude star Mu Leporis.

November

2-Crosses into the constellation of Orion the Hunter.

3-Pass 1.5 degrees from the bright star Rigel.

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

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

11- Crosses the celestial equator northward.

14-Passes closest to the Earth, at 0.358 AU distant.

15- Passes near the star Bellatrix.

23-Passes into the astronomical constellation of Taurus the Bull.

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

29-Crosses the ecliptic plane northward.

December

1-May drop back down below +10^th magnitude.

The comet actually reaches opposition 180 degrees opposite from the Sun on December 13^th. We can then say goodbye the Comet M3 ATLAS until it returns to the inner solar system mid-next century, in around 2159 AD.

Our preferred mode to hunt for comets is to simply use a pair of binoculars, and sweep the suspect field for a fuzzy ‘star’ looking like a globular cluster that stubbornly refuses to snap into focus. Watch a comet for several hours, and you just might see its slight orbital motion versus the starry background. Listed passages above near bright stars are especially handy as celestial ‘guide posts, to find each respective comet.

…and 2020 has at least one more bright comet in store: C/2020 S3 Erasmus, set to brighten up to +6^th magnitude in mid-November. More to come on that next month.

Don’t miss the Fall parade of comets, topping out astronomy in 2020.

Lead image credit: Comet M3 Atlas from October 18th. Image credit and copyright: Michael Mattiazzo.