Special to CosmicTribune.com, October 13, 2024

Excerpts from weekly Sky&Telescope report.

SUNDAY, OCTOBER 13

■ And now, even 60 minutes after sunset, the comet ‘s head is still a fine 9° high or so in the darkening sky. It’s about midway between Venus to its left or lower left, and Arcturus to its right or upper right. The head may match Arcturus, magnitude zero, for brightness.

By now T-A is predicted to grow a thin, faint antitail pointing opposite the main tail. An antitail can appear when Earth passes through the plane of a comet’s orbit and we view the thin, broad sheet of its dust debris edge-on.

At twilight’s end now, the comet is still a couple degrees over the horizon. However, when any celestial body is that low, atmospheric extinction dims it considerably.

The comet will climb higher and stay up longer through the rest of the coming week, while dimming and receding into the distance. Expect it to be about magnitude 2.5 on the evening of the 16th and mag 4 by the 21st.

The post-twilight sky grows poorer as the light of the waxing gibbous Moon grows brighter. The Moon is full on the evenings of the 16th and 17th. But on about the 20th, a window of darkness will begin to open between twilight’s end and moonrise.

The solar system’s nearest and farthest easy naked-eye objects accompany each other on Sunday and Monday evenings. Or so it seems. Saturn is 3,600 times farther away than the Moon!

MONDAY, OCTOBER 14

■ How early in twilight can you spot Saturn, magnitude +0.7, in the far background of the Moon? They’ll appear about 5° apart during evening in North America. See the scene above.

TUESDAY, OCTOBER 15

■ This evening for the Americas, the head of Comet T-A will be passing only about 1.2° south of the 6th-magnitude globular cluster M5 — “a not-to-miss opportunity for photographers,” writes Bob King. The comet’s head by now should be about 2nd magnitude.

WEDNESDAY, OCTOBER 16

■ Full Moon this evening and tomorrow evening. The Moon is exactly full at 7:26 a.m. EDT on the 17th: about halfway between these two evenings for the Americas.

■ And while comet-spotting, take note of Arcturus low in the west-northwest about 2½ fists at arm’s length to the comet’s right or lower right. Sometime around when twilight ends, you’ll find that Arcturus is the same height above the horizon as equally bright Capella in the northeast. When that happens, turn to the south-southeast, and there will be 1st-magnitude Fomalhaut at about the same height too — exactly so if you’re at latitude 43° north (Boston, Buffalo, Milwaukee, Boise, Eugene). Seen from south of that latitude Fomalhaut will appear higher; from north of there it will be lower.

THURSDAY, OCTOBER 17

■ The Great Square of Pegasus, emblem of autumn, is now high in the east-southeast after dark — still, for now, balanced on one corner (for the world’s mid-northern latitudes).

FRIDAY, OCTOBER 18

■ This is the time of year when the Big Dipper lies down horizontal low in the north-northwest when evening grows late, around 10 p.m. How low? The farther south you are, the lower.

While you’re waiting for twilight to dim enough for observing Comet Tsuchinshan-ATLAS this evening (it should be 3rd magnitude now), use your binoculars to try for Delta Scorpii, currently magnitude 1.7 or 1.8, glimmering to the left of brilliant Venus by just 1.6°.Antares, 9° left of Venus, is magnitude 1.0, twice as bright as Delta Sco.

SATURDAY, OCTOBER 19

■ The Moon, now waning gibbous, follows a few degrees behind the delicate Pleiades as they cross the sky tonight. Use your fingertip to block the Moon’s glare.

Aldebaran and Jupiter follow along farther behind the Moon.

SUNDAY, OCTOBER 20

■ Now that it’s mid-October, Deneb has replaced Vega as the zenith star after nightfall (for skywatchers at mid-northern latitudes).

■ The Orionid meteor shower should be active in the hours before dawn Sunday morning, but don’t expect to see many at all through the waning gibbous moonlight. The radiant, in Orion’s upraised club, will be high in the southeast to south by then.

■ Even if the meteors disappoint when you’re out before dawn Sunday, you can certainly catch Pollux, Mars, and Procyon forming a straight line, in that order from upper left to lower right. The three shine with fairly similar brightnesses: magnitudes +1.1, +0.3, and +0.4, respectively. Pollux is three times closer to Mars than Procyon is.

  Oct. 13-20: Welcome Comet T-A, The Sky