A telescopic image of Comet 46P / Wirtanen, taken on 6 December 2018, reveals the weak tail of the comet. Astrophotographer Alan Dyer captured this image of Comet 46P from Alberta, Canada, with a Canon EOS 6D Mark II DSLR camera on an A & M 105 mm apo breaking telescope.
Credit: Alan Dyer / AmazingSky.com /twitter
This weekend a comet will pass close by the earth, a treat for skywatchers – and for astronomers who hope to learn more about the building blocks of the early solar system.
The comet, called 46P / Wirtanen, will humble through the earth on Sunday, December 16th at 8:06 am EST (1306 GMT). The comet passes only 7,199,427 miles (11,586,350 kilometers) of the earth. This makes it one of the 10 densest comet approaches since 1950 and the 20th closest approach to a comet dating back to the ninth century.
During this close approach, the comet will be visible to the naked eye (under extremely dark skies) and provide a rare event for skywatchers, according to a statement from Auburn University in Alabama. [Amazing Photos of Comet 46P/Wirtanen By Stargazers]
To recognize the comet, "follow [the constellation] Orion's arm through his bow to the right and looking for a fuzzy blob that's green compared to the stars around it, "said Dennis Bodewits, an astrophysicist at Auburn University, in the statement." Orion is always easy to find by the bright stars that form its belt. & # 39;
Besides a treat for skywatchers, the comet event also offers a unique opportunity for astronomers. Bodewits plans to use three NASA telescopes – the Hubble Space Telescope, the Chandra X-ray Observatory and the Neil Gehrels Swift Observatory – simultaneously to follow the comet's path across the sky. He will also use the tools to collect data about the ice creams that make up the object and to study how chemical processes change the gas around it, according to the statement.
"These observations are like a space mission in reverse order, because the comet is flying past us," said Bodewits. "Because the comet comes very close to the earth, we can investigate the inner 200 kilometers [120 miles] around the core, a region that we can not solve for most of the comets. "
Comets are icy bodies that whiz through the air, releasing gas or dust. They are supposed to consist of leftover material that initially formed the solar system about 4.6 billion years ago.
Comet 46P / Wirtans is very similar to another comet, called Hartley 2. That object visits the inner solar system about every 6,5 years and was one of the main goals of NASA's Deep Impact mission, which was launched in 2005 according to the statement.
"Hartley 2 astonished astronomers because it emits much more gas than expected from the scale," Bodewits said. "Compare [the] two will enable us to learn more about how the comet activity works. "
The observations gathered during the near approach of Sunday will also provide an important context for both the Rosetta and Deep Impact missions, which are designed to study comets up close, according to the statement.
Launched in 2004, the Rosetta mission taught scientists more about the composition of the core of a comet and the origins of our solar system, Bodewits said.
"It unexpectedly found a lot of molecular oxygen gas and discovered that electron collisions can change the comet," Bodewits said in the statement. "These are both important because they tell us what kind of ice are the building blocks of our solar system and how they were changed by light and radiation from the sun."
Because 46P / Wirtanen is coming close to Earth, Bodewits is planning to observe the comet with as many telescopes as possible, he said. In turn, the data can help researchers learn more about the early solar system.
"The timing of this comet can not be improved, because our observations will enable us to apply everything we have learned from Rosetta to a completely different comet," said Bodewits.