Entries in Astronomy (18)

Monday
Oct292007

Comet Holmes: Then and Now

Earlier this evening I went outside with Zoe to look for Comet Holmes which has recently undergone something of an outburst. Immediately on stepping out of the front door it was obvious as a 2nd-magnitude star-like object a few degrees from Alpha Persei in the direction of Capella. Through binoculars it was a circular ball of fuzz, contrasting nicely with the sharp pin-points stars in Alpha Persei Cluster.  No sign of a tail.  The integrated brightness was just a little below that of Algol at maximum, say magnitude 2.3 or 2.5.

But for me Comet Holmes means the above photo taken by Edward Emerson Barnard back in 1892.  This photo appears as Plate 18 in Ball's Popular Guide to the Heavens, one of the books that sparked my interest in Astronomy when I was about the same age that Zoe is now.  This is what Ball had to say on this photo:

HOLMES' COMET AND THE ANDROMEDA NEBULA
On Nov. 6, 1892, Mr. Edwin Homes discovered in London a comet which was in many ways remarkable.  When found it was close to the great nebula in Andromeda, and its motion was so slow that, throughout the month of November, it could be photographed on the same plate with the nebula.  Plate 18 is a reproduction of a photograph taken at the Lick Observatory, on November 10th, by Professor Barnard, who describes the comet as "round and sharply defined like a planetary nebula, with a symmetrical, nebulous atmosphere surrounding it for some distance."
The after-history of this comet is very curious.  By the middle of December, it had grown so exceedingly faint and ill-defined that scarcely any telescope could show it.  But, in the middle of January, it suddenly brightened up, and condensed into a small, hazy, star-like object, after which it again became diffuse, and finally vanished.
The comet's orbit was equally remarkable.  It lay entirely between Mars and Jupiter, in the zone of minor planets; and it has even been suggested that the comet was not a comet at all, but the result of some celestial accident --such as a collision-- which had befallen an asteroid.
Sunday
Oct072007

A Nineteenth Century Daylight Meteor

Yesterday I came across this image in Astronomy, by George F. Chambers,  1914(?).   The caption reads:

Daylight meteor seen at Penshurst, Kent, June 20, 1866.  Length of coloured portion 1 degree; space traversed in 2 seconds, 80 degrees.  (J. Nasmyth)

A quick search led to The daylight meteor of 1866 June 20, Chris Trayner, WGN, Journal of the International Meteor Organization, vol. 32, no. 4, p. 122, 2004, from which comes the following account by Nasmyth:

While walking in my garden at about a quarter to eleven on the forenoon of June 20th, I was startled to see a bright red comet-shaped object rapidly moving across the clear blue sky about 35 degrees above the horizon.  The length of the meteor was about 1 degree, or twice as long as the Moon appears in diameter.  The motion was majestic, yet rapid, for it traversed a space of 80 degrees in rather less than two seconds.  The direction was from N.W. to S.E.  The advancing end of the meteor was brilliant red, with a white or shining envelope or head; the after part, or tail, was a ragged fan-shape, with a waving motion, accompanied by white vapours, and followed by a faint white vapour-trail.  It disappeared from my sight behind a mass of clouds, and I listened for some time to catch any report or sound of explosion, but I heard none.  The passage of the meteor was nearly parallel to the horizon, but with a slight dip or decline to the S.E.  It is impossible to convey by words the impression left by the appearance of this mysterious object, majestically traversing the clear blue sky during bright sunshine.  Had it made its appearance at night, the whole of England would have seen more or less of its light.

Trayner states that the meteor was seen over Sussex, Kent and from the coasts of northern France, Belgium and even Holland.  "J. Nasmyth" was almost certainly the scottish engineer James Nasmyth, who moved to Kent and took up astronomy after he retired in 1856.

Sunday
Nov192006

Leonid Meteors

I woke Zoe up at 3:45am this morning and we went out to watch for Leonid meteors.  The sky was largely clear with a little thin cloud now and then.  Our observing site, the cricket pitch in Reading University grounds, was not ideal: there are sodium street lights at about 100 metres all round, but it is the best available site close to our home.  Between 04:10 and 04:50 UT we saw 8 Leonids.  Not a meteor storm but still worth the effort.  Zoe seemed pleased, anyhow.

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