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Comet NEOWISE: As you can see in the night sky

Zealous observers of the sky turn to the sky as the comet NEOWISE, one of the brightest comets of a generation, rises ever higher among the evening stars.

Most comets fly invisibly through the solar system, usually too small and dark to be seen with the naked eye. The last frozen ice ball that gave us a big show was Hale-Bopp, a comet that was visible for almost 18 months in 1997 as it approached Earth.

The comet NEOWISE, officially designated as C / 2020 F3, was discovered on March 27 and until this week was only visible to dedicated comet viewers who were ready to wake up in the early morning. But on Monday, NEOWISE tipped into the sky after sunset and was even spotted by people living near city centers with all the light pollution.

“It is the first time in 23 years that this has been possible,” said Federica Spoto, an astronomer at Harvard & Smithsonian Center for Astrophysics. “You can watch it from your garden and you don’t need a telescope.”

To catch NEOWISE yourself, look into the northwestern sky about an hour and a half after sunset. Experts recommend walking in the darkest area for the best display. Find the Big Dipper and follow its trowel as it bends toward the horizon.

NEOWISE appears under the Big Dipper about 10 degrees above the horizon and is about as bright as the stars of this constellation. When you extend your arm, 10 degrees is about the part of the sky that is covered by your fist. Over the next few days, NEOWISE will move higher in the sky and be easier to spot, and will peak on July 23 when it approaches Earth.

With good binoculars you can see more of the comet and its spectacular dust tail. Happy viewers could even catch the weaker blue ion tail, which consists of charged particles flying from the icy core of the comet. NEOWISE is only visible to observers in the northern hemisphere and should remain bright enough to be recognized by mid-August.

For those who want to keep a souvenir of their experience, a digital camera placed on a tripod and set for a five or ten second exposure could do the trick, said Ernesto Guido, an amateur astronomer in Italy. With many cell phones, users can change the settings of their cameras and get surprisingly good results. Try to frame NEOWISE against a beautiful background like a tree, suggested Mr. Guido.

The comet NEOWISE takes its name from NASA’s near-earth infrared survey explorer (NEOWISE), a space-based infrared telescope that is dedicated to the search for potentially dangerous asteroids and comets. Researchers who run the observatory discovered the comet in March when it was facing the sun.

The comet NEOWISE came closest to our star on July 3 and came into orbit from Merkur.

“A smaller or weaker comet would have collapsed under the pressure,” said Amy Mainzer, chief investigator of the NEOWISE mission.

This is exactly what happened with comet SWAN earlier this year, which was barely visible to the naked eye in the southern hemisphere before hissing as it circled the sun. Another comet, ATLAS, disintegrated into more than two dozen parts in April.

NEOWISE comes to us from the distant outside of the solar system after spending most of his life in a cold field of icy bodies called the Oort Cloud. When comets are far from the sun, they are sluggish and do not have beautiful dust tails that can be 10 million miles long. The heat of the sun causes them to emit gas and dust and form an atmospheric envelope called a coma. The pressure of solar radiation then expands this structure into a long tail.

Comets like NEOWISE are remnants of the formation of our solar system. Because they keep the building blocks of the planets in their frozen ice, they can provide scientists with important information about our origins. Dr. Mainzer compared his approach to a mission of collecting samples and returning them to Earth, except that “the sample comes to us.”

NEOWISE does not make it back to the inner solar system for 6,800 years. So enjoy it as long as you can.

“It is very difficult for many people at the moment,” said Dr. Mainz. “But this is a chance to take a look and reconnect with the big picture.”

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