Friday, October 26, 2007

Comet Holmes tonight at the Great Lawn--if, of course, the sky is clear

Comet Holmes - 1-/24/07 -- photo MrMoorey

Passing Comet in Suprise Flare-Up, Visible To Naked Eye

By John Borland EmailOctober 25, 2007 |

Astronomy blogs and boards are buzzing today with news that a relatively obscure comet making a pass near Earth has brightened unexpectedly, to the point of looking like a supernova, say some.

The comet, called 17/P Holmes, has apparently reached the point where it is visible to the naked eye, even near well-lit areas with a near-full moon, amateur astronomers write. Holmes is in outburst mode – a point where a comet releases ice or other particles, increasing its size and reflectivity – but the magnitude of the increase has surprised everyone.

For now, the comet is visible in the Perseus constellation, in the Northern hemisphere. Charts for the astronomically minded can be found here, while the history of the comet, first discovered in 1892, can be found here.

Astronomers write that the comet had been faintly visible since July, and had begun to fade. But on Wednesday, observers around the world began reporting a dramatic flare-up, to the point where even naked eye viewing was possible.

Unfortunately, it's cloudy where I'm sitting, with no sign of clearing in the near future. Here's hoping Holmes keeps bursting.

Ben Cacace wrote yesterday :

Just saw this magnificent object from 43rd St. and 1st
Ave. naked eye and with binoculars. It's outstanding
in bins and I hope to be able to view it tomorrow **
night from the north end of the Great Lawn.

There is a decent star chart in Wikipedia:

**NOTE from Marie--Ben's "tomorrow" = TODAY, October 26

PS -- Just got another e-mail about Comet Holmes, from John Pazmino, with lots of fascinating info. I'll copy it below:


An old comet, known since the 1890s and well-behaved since then, suddenly erupted on Wednesday 24 October 2007. The outburst turned it from a dim weak comet, out of range of small scopes, to a lustrous new star equaling the brighter stars in the autumn sky. As luck fell, it was cloudy and raining on that evening in New York City and vicinity.

If the comet remains bright for the next couple days, it will be visible by eye as a new 'star' even from the City. Comet Holmes is in a slow part of its trajectory, so it'll stay in the same area of he sky for a while.

There is no way to tell how long comet Holmes will stay bright. It could fade quickly and return to obscurity within days or linger as a luminous ornament in the autumn sky for weeks.

The cause of this eruption is likely a bustout of trapped heated gases that break thru the comet's crust, much like a new volcano on Earth. Given that the comet is a loosely packed heap of rock and dirt and frozen gas, this behavior is accepted as a general feature of comets. The gases are ionized, making them glow under radiation from the Sun. When the gases dissipate or the fracture closes up, the comet settles back to its normal state.

Comet Holmes was discovered in 1892 and is has a 7-1/3 year orbit. It is the 17th periodic comet, a comet with a closed orbit that brings it near the Sun at regular intervals. It was observed regularly thru the return of 1906. Then it didn't show up again. Holmes got lost because in 1908 is passed close to Jupiter, which swang it into a new orbit. In 1964 it was recovered and followed ever since. The previous round of the Sun was in 2000.

BONUS! On the evening of the 27th, Saturday, the Moon rises in front of Pleiades star cluster. Before moonrise she was covering the Pleiades stars. By early night, the Moon moves a bit left, east, of the Pleiades,... On the other hand, if the sky have any haze, the Moon could obscure the stars and comet in higher sky.

This skywatching material is provided by NYSkies Astronomy Inc, the support service for home astronomy in the New York region. NYSkies is at,