Where's Saturn? Is that a UFO--or the ISS? What's the name of that
star? Get the answers from mySKY--a
fun new astronomy helper from Meade. AURORA
ALERT: A geomagnetic storm is underway
that could spark auroras
bright enough to see through the glare of tonight's full Moon. High
latitude obervers should be
alert for Northern Lights.
SPACESHIP SIGHTINGS:
Last night when the International Space Station
flew over Texas, photographer Bret Dahl pointed his 10"
LX200 at the moving point of light and took this
amazing picture. The ISS has grown so large, its details are
easily resolved by ordinary backyard telescopes. Tonight the details
are different: space shuttle Discovery has docked to the ISS making
the ensemble even bigger and brighter. Be
alert for flybys.
STRANGE COMET: Astronomers
around the world agree, Comet 17P/Holmes is one of the strangest
things ever to explode in the night sky. It's a comet, yet it looks
like a planet with a golden core and a green atmosphere:
Chris Shur of
Payson, Arizona, took this picture last night using his 12.5-inch
telescope and a Canon
XTi digital camera. "The comet was yellow and green, very
bright in the viewfinder," he says.
Yesterday, Comet Holmes shocked sky watchers with a spectacular
eruption, brightening almost a million-fold from 17th to 2.5th magnitude
in a matter of hours. The comet is now visible to the naked eye--even
from light polluted cities--high in the northern sky after sunset:
finder chart.
The golden hue of Holmes' core is probably the color of sunlight
scattered by comet dust, while the green fringe likely signifies
an atmosphere rich in diatomic carbon and cyanogen (substances found
in many green comets). There are reports that the fuzzball is expanding
and taking on a lopsided shape--the first signs of a tail? Amateur
astronomers are encouraged to monitor developments. After sunset,
point your backyard
telescope at the extra "star" in the thigh of Perseus.
Comet
17P/Holmes Photo Gallery
[sky map]
[ephemeris]
[3D orbit]
[Night
Sky Cameras]
BIG FULL MOON: Tonight's
full Moon is the biggest full Moon of 2007. It's no
illusion. Some full Moons are genuinely larger than others and
this one is a whopper. Why? Read the answer below.
Left: A big, bright perigee Moon.
RIght: A lesser apogee Moon.
The Moon's orbit is an ellipse with one side 30,000 miles closer
to Earth than the other. The full Moon of Oct. 25-26 is located
on the near side, making it appear as much as 14% bigger and 30%
brighter than lesser full Moons we've seen earlier in 2007.
In the language of astronomy, the two ends of the Moon's orbit
are called "apogee"
and "perigee."
Apogee is the farthest point, perigee the nearest: diagram.
This week's full Moon is a "perigee Moon" with extra-high
"perigean
tides."
The Moon is 14% bigger, but can you actually tell the difference?
It's not so easy. There are no rulers floating in the sky to measure
lunar diameters. A fun experiment: Take a friend outside tonight
and ask if they notice anything unusual about the Moon. Explain
perigee after they answer.
October
2007 Aurora Gallery
[September
Gallery] [Aurora Alerts]
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