What time will comet A3 be visible tomorrow? Comet A3, also known as Comet Tsuchinshan-ATLAS (C/2023 A3), is now putting on a show to those in the Northern Hemisphere.
It’s brightened and is visible in in the east before sunrise. In late-October. it will become bright in the west after sunset.
Will you see the comet on Sunday? With some good planning, clear weather and well-timed observing, comet A3 and its bright tail could make an eye-catching sight — if you know when and where to look — with the bonus sight of “Earthshine” on the nearby crescent moon.
Why Comet A3 Is Getting Brighter — And When To See It
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.
Those two dates are key times to view the comet, which will have two distinct observing periods for those in the Northern Hemisphere.
Where To See Comet A3: Sunday, Sept. 29
Position: east-southeast, 22.3 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: 58.9 million km
Comet’s distance from Earth: 124.9 million km
This morning, comet A3 will be visible close to the east-southeast an hour before sunrise. It will be placed below a 9%-lit waning crescent moon and Regulus, the brightest star in the constellation Leo.
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.
Once you’ve looked at the comet, look at the moon’s dark limb for “Earthshine”—sunlight reflected from our planet’s oceans and ice caps onto the lunar surface. It’s just strong enough to subtly illuminate the moon’s limb.
When To See The Comet
- Sept. 27: comet A3 will reach its perihelion — the closest it gets to the sun — at about 36 million miles (58 million km). It will be visible in the east an hour before sunrise from Sept.27 through Oct. 3.
- Oct. 12: comet A3 will reach its closest to Earth at about 44 million miles (71 million km) from Earth. It will be visible in the west an hour after sunset from Oct. 12 onwards, but fading each night.
During both of these periods, its dusty tail will reflect sunlight precisely because of its favorable position between the sun and Earth. It’s known as “forward scattering” to astronomers because it scatters sunlight in the direction of Earth — and into the eyes of observers.
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.
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