Stargazers in the Philadelphia region are in for a double celestial treat this week with a rare comet and a mega supermoon set to shine in the night sky.

“This could be a once-in-a-lifetime experience,” Franklin Institute lead astronomer Derrick Pitts said of Comet Tsuchinshan-ATLAS, which appeared over the Philadelphia region this week. “So bring some friends and enjoy the view.”

The comet shines brightest, just as the supermoon Hunter’s Moon shines even bigger than normal.

With all this excitement in the night sky, we have your guide to catching a glimpse of both Comet Tsuchinshan-ATLAS and the supermoon. Here you will find answers to your questions.

Let’s talk about Tsuchinshan-ATLAS first.

What is a comet?

“Comets are frozen remnants of the formation of the solar system and are composed of dust, rock and ice,” says NASA. The comets are “snowballs of frozen gases, rocks and dust that orbit the sun.”

Comets “are a few to tens of kilometers wide, but as they orbit closer to the sun, they become warmer and spew gases and dust into a glowing head that can be larger than a planet,” NASA says. “This material forms a tail that stretches for millions of kilometers.”

What you can actually see is that tail of heated debris.

And there is no shortage of comets waiting to be discovered.

“There are probably billions of comets orbiting our sun in the Kuiper Belt and the even more distant Oort Cloud,” NASA says.

“Comets are more fragile than people may realize, thanks to the effects of passing close to the sun on their internal water ice and volatiles such as carbon monoxide and carbon dioxide,” said NASA astronomer Bill Cooke, chief of NASA’s Meteoroid Environment Office. Marshall Space Flight Center in Huntsville, Alabama.

NASA wrote in a Watch the Skies blog post:

The brightness of comets is measured on the same scale we use for stars, a scale that has been in use since about 150 BC, when it was devised by the ancient scholar Hipparchus and refined by the astronomer Ptolemy. Stellar magnitude is measured on a logarithmic scale, making a star of magnitude 1 exactly 100 times brighter than a star of magnitude 6. The lower the number, the brighter the object, making it more likely to be clearly visible, whether with a telescope or the naked eye.

“Normally, a comet would have to reach magnitudes of -6 to -10 to be seen in daylight,” Cooke said. “That is extremely rare.”

Perhaps no comet is more famous than Halley’s Comet, which passes by Earth every 75 to 76 years. “Halley is the only known short-period comet that is regularly visible to the naked eye from Earth, and the only naked-eye comet that can appear twice in a human lifetime,” NASA says.

Where does comet Tsuchinshan-ATLAS come from and how did it get its name?

This comet is much rarer than Halley’s and may not return, according to astronomers.

“The Oort Cloud comet, named C/2023 A3 Tsuchinshan-ATLAS, was discovered in 2023 and approached the inner Solar System in its highly elliptical orbit for the first time in documented human history,” NASA wrote in a Watch the Skies blog post. “It was identified by observers from China’s Tsuchinshan – or ‘Purple Mountain’ – observatory and an ATLAS (Asteroid Terrestrial-impact Last Alert System) telescope in South Africa. The comet was officially named in honor of both observatories.”

According to lead astronomer Derrick Pitts of the Franklin Institute, the comet has likely been in orbit for more than 80,000 years.

This could be a one-time event, as NASA updated its projections earlier this week: “the comet’s path could remove it from the solar system altogether.”

When will the comet be visible?

The comet came within about 45 million miles of Earth on October 12, 2024, according to NASA’s Earth Observatory.

Tsuchinshan-ATLAS first appeared low in the west just after sunset in the early night sky that Saturday, Pitts said in a Facebook video. In the following evenings it moved higher into the sky and became more visible.

“At maximum visibility in the Northern Hemisphere, Tsuchinshan-ATLAS brightness is estimated to be between 2 and 4,” according to Watch the Skies. ‘For comparison, the brightest visible star in the night sky, Sirius, has a magnitude of -1.46. At its brightest, Venus’s solar reflection has a magnitude of -4. The International Space Station sometimes reaches a relative brightness of –6. “

On October 15, the comet had a magnitude of 3.3, NASA said.

With sunset at 6:19 p.m. Wednesday, the best time to go outside is between 6:50 and 7 p.m., said NBC10 First Alert Weather meteorologist Bill Henley. “Look at the western horizon, where the comet will set.”

The comet will grow darker as it moves further from the sun each night and should disappear from view by early November, astronomers said.

“And enjoy the view,” Cooke advised.

What are the best conditions to view the comet?

“The comet’s head – made up of the nucleus and coma – along with the tail, should be visible again under a clear, dark sky,” Pitts said.

Grab a compass to orient yourself.

“Choose a dark vantage point just after nightfall, Cooke recommended,” NASA said. “Looking southwest, about 10 degrees above the horizon, identify the constellations Sagittarius and Scorpio. Tsuchinshan-ATLAS should be visible between them. On October 14, the comet may remain visible halfway between the bright star Arcturus and the planet Venus.”

“Stars and comets will shine brighter against the dark background of the sky, making this a near-ideal opportunity to see the once-in-80,000-year comet,” Henley said.

Pitts advises grabbing binoculars “to follow the comet.”

Henley agrees: “For the best view, try to find a spot away from city lights to minimize light pollution. Although the comet may be visible to the naked eye, binoculars or a small telescope will give you a clearer and more detailed view , especially if you want to see its tail.”

Now to that mega-supermoon.

“Be careful,” Henley said. In addition to the comet, you’ll also want to check out the nearly full Hunter’s Moon rising in the eastern sky. It will be the brightest supermoon of the year. Although the moon won’t be fully illuminated until Thursday morning, it will still be a spectacular sight Thursday evening, much viewing pleasure!”

What is a supermoon?

“The term ‘supermoon’ was coined in 1979 and is often used to describe what astronomers would call a perigean full moon: a full moon that occurs near or at the moment when the moon is at its closest point in its orbit around Earth is located,” says NASA. wrote.

“A supermoon occurs when the moon’s orbit is at its closest (perigee) to Earth at the same time the moon is full,” according to NASA.

Basically, it appears to be a larger than normal full moon.

Why is this October supermoon so great?

The names alone of this megamoon make him special. “The next Full Moon is a Supermoon; the Hunter’s Moon; the Travel Moon, the Dying Grass Moon, or the Sanguine or Blood Moon; the beginning of Sukkot; Sharad Purnima, Kumara Purnima, Kojagari Purnima, Navanna Purnima Kojagrat Purnima or Kaumudi Purnima ; the end of Vassa and Pavarana; the end of the Phaung Daw U Pagoda Festival;

The third of 2024’s supermoons will come within about 220,000 miles on Wednesday night, making it appear even bigger and brighter than previous supermoons of August and September.

“Scientists point out that only the keenest observers can distinguish the subtle differences,” the Associated Press reported. “It’s easier to detect the change in brightness: a supermoon can be 30% brighter than average.”

When is the best time to watch October’s supermoon?

The moon will officially become full on Thursday morning (October 17, 2024) at 7:26 a.m. ET, according to NASA. However, the moon will be a “supermoon,” arriving at perigee on Wednesday at 8:48 PM ET.

The best times to see it in all its glory are from Wednesday evening to Thursday morning before sunrise. Henley said the moon will rise in the east on Wednesday, October 16 at 5:51 PM ET.

However, it should appear full for about three days at this time, from Tuesday evening through Friday morning, Johnston said.

Could the moon actually deter the comet?

The moonlight will take away some of the comet’s visibility, Cooke told the Associated Press.

“Most astronomers hate the full moon because its bright light interferes with seeing other objects. So it’s a little hard for us to wax poetic about it, even though it’s the biggest supermoon of 2024,” he said in an email.

The biggest question: Will the weather over the Philadelphia region cooperate with the celestial double feature?

Simple answer: yes!

“Over the next few evenings, the weather will be just about perfect for catching a rare glimpse of the comet lighting up the night sky,” said meteorologist Bill Henley. “A large area of ​​high pressure is building in the Philadelphia area, giving us clear skies and cold nights. This will also reduce moisture and particles in the air, giving us a cleaner and clearer view of the night sky.”

“Temperatures will drop into the 40s by the time the comet dips below the horizon at 8:32 PM on Wednesday, October 16, 2024, so be sure to dress warmly,” Henley said.

Don’t worry if you miss the comet Wednesday night, as Henley said clear skies will continue for the next few days.

Enjoy!