What time will comet A3 be visible tomorrow? Comet A3, also known as Comet Tsuchinshan-ATLAS (C/2023 A3), is currently shining brightly for those in the Northern Hemisphere and will on Monday, Sept. 30 appear alongside a crescent moon.
The two will be visible to naked eyes in the east before sunrise, which means it’s necessary to rise very early before they get swallowed-up by the creeping light of dawn. In late-Oct. it will become bright in the west after sunset.
Why And When Comet A3 Is Visible
Comet A3 is moving to a position in between the Earth and the sun. On Sept. 27, comet A3 reached its perihelion — the closest it gets to the sun — at about 36 million miles (59 million km). Comet A3 will get closest to Earth on Oct. 12, when it will pass about 44 million miles (71 million km) from Earth.
The mornings and then evenings around those two dates are key times to view the comet — and we’re now deep into that first observing window.
Here’s how to see comet A3 and the moon on Monday, Sept. 30, 3034:
Where To See Comet A3: Monday, Sept. 30
Position: east-southeast, 21.6 degrees from the sun in Leo
Time: an hour before sunrise where you are (around 07:00 in the U.S.)
Expected magnitude: +4.5
Comet’s distance from the sun: 59.6 million km
Comet’s distance from Earth: 118.5 million km
This morning, comet A3 will be visible a closer to the east-southeast an hour before sunrise. It will shine to the lower-right of a 5%-lit waning crescent moon. Regulus, the brightest star in the constellation Leo, will shine above the pair.
It should be visible just above east-southeast about 75 minutes before sunrise and will be best seen in astronomical darkness, which will last until about 60 minutes before sunrise.
Also look at the moon’s dark limb for “Earthshine” — sunlight reflected from our planet’s oceans and ice caps — which is strong enough to subtly illuminate the dark lunar surface. It looks incredible through any pair of binoculars.
Seeing The Leo Constellation
Comet A3 will be visible below the constellation Leo, whose bright stars you may be able to make out if you have dark skies. One of the zodiacal constellations (which simply means that the sun appears to pass in front of its stars every year as seen from Earth), Leo is, of course, thought to represent the shape of a lion.
Find its brightest star, Regulus, at one of the animal’s front paws and, then look for Denebola at the end of its tail. Both are relatively close to our sun — Regulus at 79 light years and Denebola at 36 light years.
Between Regulus and Denebola — roughly where the moon is this morning — are are the M96 (Leo I Group) of galaxies, a cluster of about nine galaxies about 30 million light-years from Earth. As you gaze at comet A3 close to Leo, note that you’re looking looking outside the Milky Way and into deep space — and that comet A3 is a mere 118.5 million kilometers distant.
Check my feed every day this week and next for a daily “comet tracker” with sky-charts and tips for viewing Comet A3.
Wishing you clear skies and wide eyes
