NASA's NEOWISE captures Comet C/2014 Q2 (Lovejoy)

Credit: NASA/JPL-Caltech

Comet C/2014 Q2 (Lovejoy) is one of more than 32 comets imaged by NASA's NEOWISE mission from December 2013 to December 2014.

This image of comet Lovejoy combines a series of observations made in November 2013, when comet Lovejoy was 1.7 astronomical units from the sun. (An astronomical unit is the distance between Earth and the sun.)

The image spans half of one degree. It shows the comet moving in a mostly west and slightly south direction. (North is 26 degrees to the right of up in the image, and west is 26 degrees downward from directly right.)

The red colour is caused by the strong signal in the NEOWISE 4.6-micron wavelength detector, owing to a combination of gas and dust in the comet's coma.

Comet Lovejoy is the brightest comet in Earth's sky in early 2015. A chart of its location in the sky during dates in January 2015 is at photojournal.jpl.nasa.gov/catalog/PIA19103 .

Comet Lovejoy (C/2013 R1) reaches a pivotal point

Comet Lovejoy (C/2013 R1) reaches a pivotal point in its orbit next week when it comes closest to the sun.

It will still be visible to earthbound skygazers, astronomers say.

While not a sun-grazer like its sibling comet, ISON, which flew into the sun and vapourised last month, Lovejoy is expected to reach so-called perihelion on Christmas Day.

"When the comet comes close to the sun, the solar winds push material off of it," said Jin Koda, an assistant professor in the department of astronomy and physics at Stony Brook University.

Those winds force dust, ice and vapours off the core into the characteristic tail. Koda has captured some of the world's best photos of Lovejoy's journey.

Last week, the comet could be spotted near the Big Dipper's handle but it's moving at nearly 300 miles per second and can now be spotted near an entirely different star cluster-Hercules.

Experts recommend evening viewing because the moon may hinder a good sighting before dawn.

With a pair of binoculars Lovejoy should be easily visible around 6:30 p.m. EST until the end of the year.

"If you're looking east, the Big Dipper is scraping the horizon and its bowl is pointing on an angle up near the North Star," said comet tracker Dan Malerbo, an astronomer with the Buhl Planetarium and Observatory in Pittsburgh.

"Hercules is located to the left of the Big Dipper and has the shape of a keystone," he said.

"This comet isn't getting too close to the sun. ISON was about 700,000 miles from the sun. This one is 70 million miles away."

Image of Comet Lovejoy (C/2013 R1) captured by the Subaru Telescope's Suprime-Cam on December 3, 2013 (Hawaii Standard Time). 

The wavelength was at 450 nm (B-band), with a 180 second exposure. 

Credit: NAOJ, data processing by Masafumi Yagi (NAOJ)

A team of astronomers from Stony Brook University (the State University of New York at Stony Brook), the National Astronomical Observatory of Japan (NAOJ), and others used Suprime-Cam, Subaru Telescope's wide-field, prime-focus camera, to capture an image of the intricate flow of Comet Lovejoy's (C/2013 R1) ion tail.

The instrument's combination of a wide field of view and high spatial resolution provides a clear delineation of the complex, wiggling streams in the comet's tail.

At the time of this observation, at around 5:30 am on December 3, 2013 (Hawaii Standard Time), Comet Lovejoy was 50 million miles (80 million km) distant from Earth and 80 million miles (130 million km) away from the Sun.

Comet Lovejoy's wiggle shows Sun's variable coronal magnetism

Visualization of the coronal magnetic field through which comet Lovejoy passed. 

The magenta arc indicates Lovejoy's path, which traversed both open (orange) and closed (blue) magnetic field lines. 

The unexpected directions and changes in tail motion were found to be consistent with the orientation and variation of the magnetic field along this path, which was determined from a sophisticated computer model of the solar corona. Credit: Cooper Downs

A team of researchers studying comet Lovejoy has discovered that as the ball of ice passed through the sun's corona in December 2011, its tail wiggled in a way that allowed them to better understand coronal magnetism.

In their paper published in the journal Science, the team says observations of Lovejoy's close call with the sun have helped them improve models used to describe the irregular nature of coronal magnetism.

Comet Lovejoy is part of a class of comet's known as Kreutz sungrazers—they are believed to be remnants of a much larger comet that broke apart hundreds of years ago.

They're called sungrazers because they have a tendency to strike the sun's corona at an angle. Most break apart and disappear—Lovejoy did not.

Instead it spun around the sun at very high velocity and shot back out into space, only to break apart several days later. Sungrazers offer researchers a unique way to study the sun's corona—it's too hot to send a probe—temperatures typically hover in the millions of degrees.

Instead they can watch what happens to comets as they are impacted by intense temperatures and magnetism.





More information: 
Probing the Solar Magnetic Field with a Sun-Grazing Comet, Science 7 June 2013: Vol. 340 no. 6137 pp. 1196-1199 DOI: 10.1126/science.1236550

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