Bright-Green Comet Headed Our Way On September 10, Makes Closest Approach In 72 Years

You might want to keep your telescope or binoculars close on Monday, as a beautiful green comet is about to grace us with its presence bright and early in the morning, reports Space.

Known as Comet 21P/Giacobini-Zinner, 21P, for short, the celestial body is slowly making its way toward Earth, gearing up for a big encounter on September 10.

While the comet is periodic, popping into our neck of the woods once every 6.6 years in its journey around the sun, next week’s visit is a pretty important one, notes CNET.

That’s because Monday’s reunion will be the comet’s closest approach to our planet in the last 72 years.

This year, Comet 21P will be passing within 58.6 million kilometers (36.4 million miles) of Earth — “relatively close” for a comet, states astronomer and NASA ambassador Eddie Irizarry.

The same distance is also the closest one possible between Earth and Mars. In fact, that’s exactly how far the two planets have been from each other over these past few weeks, ever since Mars made its historic close approach to Earth at the end of July — the closest in 15 years, as reported by the Inquisitr.

The video below, uploaded on YouTube by Pablo Lewin Productions, LLC, shows Comet 21P as seen through a telescope on July 18 — a prelude to what can be expected next week.

Twice As Wide As Jupiter

There are two things you need to know about Comet 21P: it is relatively bright and pretty huge.

According to Irizarry, the comet’s nucleus is only about a mile wide (or around two kilometers). However, Comet 21P comes wrapped in a massive coma, also known as a cometary atmosphere, fueled by the heating core.

The closer the comet comes to the sun, the more its core gets heated, leaking out gas that envelops its entire body. This gaseous coma is currently estimated to be some 180,000 miles (about 290,000 km) in diameter, which makes it twice as wide as Jupiter, explains Irizarry.

The last time we got to see a green comet of this size was in early August, when PANSTARRS C/2017 S3 came more than twice as close to Earth — close enough to be spotted with the naked eye, the Inquisitr reported at the time.

Meanwhile, Comet 21P seems to glow in more of a bright-green hue and will only be visible through a telescope or a solid pair of binoculars, notes Irizarry.

“Some images show the comet’s coma as a green color, which indicates the comet has cyanogen and diatomic carbon, gases that glow in a green color as they’re illuminated by sunlight,” he wrote for EarthSky.

Comet 21PGiacobini-Zinner
Comet 21P/Giacobini-Zinner as photographed on August 18 from Moscow, Russia.

Comet 21P will be reaching perihelion (or the closest point to the sun in its highly elliptical orbit) in the early hours on Monday morning, at around 2:40 a.m. EDT (06:40 GMT). That’s when it will shine the brightest and offer the best viewing opportunity.

When it finally swings by, the comet “is expected to reach a visual magnitude of 6.5 to 7,” meaning that “it will not be visible to the eye… but nearly,” says Irizarry.

To catch a glimpse of the bright-green comet at its brightest, “point your gaze eastward to the modern constellation Auriga — home of Capella, the ‘Goat Star’ — after midnight and before dawn,” advises Space.

One thing is certain, namely that you won’t want to miss the occasion of glancing at Comet 21P on Monday. If you do, you’ll have to wait another 40 years to witness another close approach, as the next time this celestial body will cozy up to Earth will be on September 18, 2058.

A Meteor Shower To Boot

Another cool thing about Comet 21P is that it is the source of the Draconid meteor shower, an annual celestial display named after the Draco constellation (“the Dragon”) from where it appears to radiate.

While a fairly modest meteor shower, the Draconids can still warrant a pleasant night out under the dark sky. According to NASA meteor expert Bill Cooke, star gazers can expect to see about five to eight shooting stars during the peak of the Draconid meteor shower, which this year occurs on October 9, reports Space.

That’s one more reason to keep your eyes on Comet 21P next week.

“It could be the closest thing to a real-life dragon in the night sky, and you can catch its flight with a pair of binoculars,” notes CNET.