Mystery Comet Explodes into Brightness

October 26, 2007
Mystery Comet Explodes into Brightness
Comet 17P/Holmes is in super-outburst! It brightened by a factor of one million in less than 24 hours. This comet currently appears as a fuzzy, yellowish star-like object in the constellation Perseus and is well-placed for northern hemisphere observers. Credit: Chris Schur

A once-faint comet has made a sudden leap from obscurity to center stage. Comet 17P/Holmes, now visible to northern hemisphere residents, increased its brightness by a factor of one million this week, going from magnitude 17 to 2. This makes it visible to the unaided eye as well as binoculars and telescopes, offering a unique viewing opportunity for sky watchers.

"This is a terrific outburst," said Brian Marsden, director emeritus of the Minor Planet Center, which tracks known comets and asteroids. "And since it doesn’t have a tail right now, some observers have confused it with a nova. We’ve had at least two reports of a new star."

Comet Holmes is located in the constellation Perseus and is visible for most of the night. In fact, for observers at the latitude of Boston, the comet is circumpolar, never setting below the horizon. In appearance, it resembles a fuzzy, yellowish star.

The comet could fade in a matter of days or weeks, so astronomers recommend that viewers take a look now. Sky charts showing where to look for the comet are online at … g/home/10775326.html .

Amateur astronomer Edwin Holmes, who was looking at the Andromeda galaxy at the time, discovered Comet Holmes in 1892. The comet has presented a mystery to astronomers ever since. It likely was undergoing a similar outburst when discovered, since it reached 4th magnitude and was faintly visible to the unaided eye. After fading, it brightened again by a factor of 100 in January 1893 before fading again for good.

The comet orbits the Sun once every 7 years at a distance of about 200 million miles (compared to Earth’s 93-million-mile orbit). As a result, it was re-observed in 1899 and 1906 before being lost for nearly six decades. Based on a prediction by Marsden, the comet was recovered in 1964.

"Since then, it’s been behaving well – until now," says Marsden.

On October 23rd, the comet was a dim 17th magnitude, 25,000 times too faint to be seen with the unaided eye. One day later, it had brightened to 7th magnitude, and the most recent observations peg it at magnitude 2 to 3: an increase of a factor of one million. (The magnitude scale used by astronomers is logarithmic.)

"When the Deep Impact probe hit Comet 9P/Tempel, there was almost no change in brightness," says Marsden. "This outburst by Comet Holmes is extreme!"

Indeed, the outburst has left experts scratching their heads. How could a tiny comet, whose nucleus is no more than two miles across, grow so bright so fast? Perhaps a crack opened in the comet’s surface, exposing fresh ice to the sun and causing an explosive eruption of dust and gas. No one knows for sure. Undoubtedly, professional astronomers will be studying it closely in the weeks to come.

Sky coordinates for Comet 17P/Holmes can be found on the Minor Planet Center website at … es/Comets/0017P.html .

Source: Smithsonian Astrophysical Observatory in Cambridge

Explore further: TESS rounds up its first planets, snares far-flung supernovae

Related Stories

Comet Finlay surprise outburst visible in binoculars

January 19, 2015

Lost sleep at night, fingers tapping on the keyboard by day. Darn comets are keeping me busy! But of course that's a good problem. Comet 15P/Finlay, which had been languishing in the western sky at dusk at magnitude +10, ...

The comet with a broken heart

April 25, 2006

Comet P73/Schwassmann-Wachmann 3 (SW 3) is a body with a very tormented past. This comet revolves around the Sun in about 5.4 years, in a very elongated orbit that brings it from inwards the Earth's orbit to the neighbourhood ...

A new sungrazing comet may brighten in the evening sky

February 25, 2015

A newly-discovered comet may soon become bright enough to see from a sky near you. Originally dubbed SOHO-2875, it was spotted in photos taken by the Solar and Heliospheric Observatory (SOHO) earlier this week. Astronomer ...

A possible meteor shower from Comet ISON?

January 15, 2014

Hey, remember Comet C/2012 S1 ISON? Who can forget the roller-coaster ride that the touted "Comet of the Century" took us on last year. Well, ISON could have one more trick up its cosmic sleeve –although it's a big maybe—in ...

Recommended for you

Making stars when the universe was half its age

January 18, 2019

The universe is about 13.8 billion years old, and its stars are arguably its most momentous handiwork. Astronomers studying the intricacies of star formation across cosmic time are trying to understand whether stars and the ...

Saturn hasn't always had rings

January 17, 2019

One of the last acts of NASA's Cassini spacecraft before its death plunge into Saturn's hydrogen and helium atmosphere was to coast between the planet and its rings and let them tug it around, essentially acting as a gravity ...


Adjust slider to filter visible comments by rank

Display comments: newest first

2 / 5 (3) Oct 26, 2007
"Indeed, the outburst has left experts scratching their heads."

This seems to be a common occurence with regard to comet theory.

A crack? More likely the comet has passed through a particularly dense electric field. A similar process is responsible for the emergence of the comets tail, as it approaches our Sun. The Deep Impact event has shown that comets are not "dirty" ice balls or icy dirtballs, but far more complex. Almost nothing predicted about comets, prior to close observation, has been confirmed. Plasma cosmology tells a different tale of comets, and presents far fewer mysteries. In fact, recent close-up observations have shown strong support for the paradigm.
1.3 / 5 (3) Oct 26, 2007
And from the peanut gallery: The region it passed through could have more Dark Matter?
1 / 5 (3) Oct 27, 2007
I've been waiting for this article to appear on Physorg... And, once again, MrGrynch already beat me to it...

The increase in brightness is an electrical discharge.
1 / 5 (1) Oct 30, 2007

Comet 17 P Holmes%u2019s super outburst is depending on hypothesizes of this commenter. These hypothesizes are 1. Early warning for global seismic hazards EWGSH 2. The theory of connecting universe with CME 3.The principle of planetary seismic hazards 4. The principle of comets and asteroids%u2019 seismicity 5. The principle of Meteorite.

The Solar, stellar magnetic wind after emission rushes ahead in the space with their Energized powers. This magnetic storm creates on the Earth, aurora, climate change, radio disturbance and seismic hazards.

The Sun is responsible factor during the process and the concentrated towards it suddenly the discovery of EWGSH was accidental due to this. The hypothetical entity of EWGSH is discovered by the commenter. Early warning for global seismic hazards (EWGSH) theory is based on solar activity like coronal mass ejection CME - sun spots - magnetic disturbance. For farther detail of this theory and early warning for global seismic-global Earth quake activity.

Due to magnetic storm many other activities including seismic activity occurs on the all objects of solar system besides the Earth to which I name it as %u201CPrinciple of planetary seismic activity%u201D (Magnetic storm shows its force on the Earth after exploring the journey of 150 million from the Sun. This way seismic activity occurs on the comet by the effect of magnetic storm as it comes near the Sun. The rubble-pile are scattered in the space due to increase to velocity. - %u2019Ejection velocity exceed escape velocity%u2019. As a result when the earth or any planet arrivals this orbit path there happens %u201CMeteorite%u201D on the Earth. The perseids, caused by Swift -Tuttle comet rubble, is on of the largest and most reliable meteor showers on record.)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.