A "dirty snowball" that comes around about once every 80,000 years is causing a stir in the skies over Connecticut this week. Comet Tsuchinshan-ATLAS (also known as C/2023 A3 and Comet A3) will be visible for the next few nights, and we only need to use our naked eyes to see it.
Comet Tsuchinshan-ATLAS is the brightest of its kind since Comet NEOWISE, which was also seen with the naked eye even in large cities back in 2020. Comet NEOWISE got its name because the object was first discovered by the Wide-field Infrared Survey Explorer (WISE) space telescope employed by the NEOWISE program. NEOWISE earned the nickname "lockdown comet" because it appeared during the COVID-19 pandemic in July 2020.
NASA calls comets "cosmic snowballs of frozen gasses, rock and dust that orbit the sun." As a comet's orbit brings this dirty snowball close to the Sun, it heats up and ejects gasses and dust, giving the appearance of a huge glowing head. A comet's head looks as large or larger than most planets in the sky. The comet's tail, made up of gasses and dust, can stretch away from the sun for several millions of miles. Comet Tsuchinshan-ATLAS' tail is estimated to be around 18 million miles long.
Comet Tsuchinshan-ATLAS was named after the two observatories that independently discovered it last year. Until about Oct. 8, the comet was primarily visible in the Southern Hemisphere and the tropics, but now the Northern Hemisphere has good opportunities to get a glimpse of it through at least Oct. 21.
The International Space Station crew had a front-row seat to the comet this September. They saw it as it approached the closest point to the sun in its elliptical orbit. The comet's image was captured as it sailed through the inner solar system.
Not all comets can survive their travels near the sun because the star's gravitational and radiation forces can destroy them. Those forces can break up comets into pieces and disintegrate them. Comet Tsuchinshan-ATLAS survived its close encounter with the sun.
The next few nights, the time to view Comet Tsuchinshan-ATLAS is about 45 minutes after sunset. Find a location with an unobstructed view of the western horizon. The lower the view on the horizon, the longer your opportunity to view the comet as it streaks through the sky.
After the full moon on Oct. 17, the moon's light will interfere less with comet viewing. The comet's path will take it higher and higher in the night sky until around Halloween night, when it will start to dim and become more challenging to see with the naked eye.
Weather conditions will comply to permit viewing the comet for the next several nights.
Don't forget to grab a jacket, as it will be a bit chilly. The National Weather Service has issued freeze warnings for most of Connecticut overnight into Thursday morning. Skies should be clear to mostly clear every night through at least Monday.
The next time Comet Tsuchinshan-ATLAS comes back around here won't be until about 80,000 years from now.
This week's comet is one of a few celestial shows that have appeared in the sky this month. The Draconid meteor shower occurred early in October, followed by an awesome appearance by the northern lights last week.
There is at least one more sky spectacle to come this month. The Orionid meteor shower, with up to 20 meteors per hour at its peak, is coming on Oct. 21 and 22.