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The annual Perseid meteor shower will peak before
dawn on Aug. 12. This year the Perseids will be competing with the nearly
full moon at first, but after the moon sets there will be many bright
streaks in the sky.
This shower is one of the most popular every year because it happens on
warm summer nights, when gazing at the starry sky is a pleasure by itself.
Many observers take advantage of this by camping out for the event. After
the moon sets around 2 a.m. local time, when viewing conditions are ideal,
you can expect to see 60 to 90 bright meteors per hour in a clear sky,
some with smoke trails that last several seconds after the meteor has
vanished.
The Perseids will be visible for most of August, though there will be
fewer meteors to see the farther from the peak date you watch. If the peak
on Aug. 12 is hidden by clouds, try looking for meteors again as soon as
the night sky is clear.
Avoid artificial lights as much as possible to minimize the effect of
local light pollution, which can obscure as many as half of the meteors.
Try facing east if you have a clear view in that direction, and look about
half-way up the sky from the horizon. You won't need binoculars or a
telescope -- the meteors move much too fast for that. The chances of
seeing a fireball will be greatest near dawn, when Earth is moving head-on
into the meteor stream.
The Perseids may appear anywhere in the sky, but they will seem to
originate from a point called the radiant in the constellation Perseus,
which gives the meteors their name. The higher the radiant is above the
northeastern horizon, the more meteors will be visible. Perseus is just
north of the W-shaped constellation Cassiopeia in the Milky Way, with the
bright stars Capella and Aldebaran and the Pleiades star cluster below it.
Meteors near the radiant will have short trails because we see them nearly
end on, while those far from the radiant will look longer because they are
seen from the side.
Most meteor showers happen when Earth crosses the orbit of a comet. The
meteors are caused by particles released from the comet's nucleus and left
behind in space. The Perseids come from Comet Swift-Tuttle. As Earth plows
through this stream of comet debris, ranging in size from sand grains to
pebbles, each particle slams into our atmosphere at a speed of more than
50 kilometers per second and burns up almost instantly from friction with
air molecules. The resulting heat momentarily creates a streak of glowing
air that we see as a meteor (sometimes called a "shooting star" or
"falling star"). All of this happens about 50 miles above the ground,
regardless of how close some meteors may appear.
More information about the Perseids and other meteor showers is available
at http://www.skyandtelescope.com/observing/objects/meteors.
Planets
Jupiter will appear in the southeast each night as the sky darkens after
sunset, and it will dominate the southern sky all night. Observers with
telescopes will have several hours of good viewing before atmospheric
disturbances start interfering as the planet sinks lower.
Venus will be the "evening star" low in the west after sunset, easily
outshining everything else in that part of the sky. During the first two
weeks of August, Venus will close in on Saturn to its upper left (south),
passing close by the bright star Regulus on Aug. 5.
Venus and Saturn will be closest on Aug. 13. They will be joined by
Mercury between Aug. 14 and 16, when the three planets will form a tight
triangle. The triangle will be different each night as the planets change
places. For observers at mid-northern latitudes, the whole group will be
low in the western sky just 30 minutes after sunset, and only Venus will
be easy to find without binoculars. People farther south will see these
planets significantly higher above the horizon. There won't be another
trio of planets this close together until 2011.
Mars will be more than 100 times dimmer than Venus, about the same
distance to the upper left of Saturn as Venus is to Saturn's lower right
on Aug. 1. You'll need binoculars to spot Mars in the bright twilight.
Viewing information and graphics for the planets are available at
http://www.space.com/spacewatch/.
Solar eclipse
A total eclipse of the sun will occur on Aug. 1 across far-northern
Canada, the Arctic, Siberia and northern China. People in much of Europe,
the Middle East and southern Asia will see at least a partial eclipse. For
details see http://www.skyandtelescope.com/observing/home/25521314.html.
Lunar eclipse
The moon will pass through Earth's shadow on the night of Aug. 16-17,
causing a deep partial eclipse of the moon for those in South America,
Africa, Europe and most of Asia. A map showing where the eclipse will be
visible can be seen at
http://www.skyandtelescope.com/observing/highlights/25523074.html.
Light pollution
If you look at the constellation Cassiopeia on a clear summer night, and
you can't see the Milky Way sprawling high across the sky from the
northern to the southern horizon, then your sky has significant light
pollution -- and that's the case for about two-thirds of the world's
population. See http://www.darksky.org/ for information on this dimming of
the night sky caused by excessive artificial lighting, much of which is
wasted.
Moon phases
The moon will be at first quarter on Aug. 8, full on Aug. 16, at third
quarter on Aug. 23 and new on Aug. 30.
Questions about space
and
astronomy, and comments and suggestions about this SkyViews
site are welcome. Write to Jay Respler, JRespler@superlink.net
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Sky Views is compiled by Jay
Respler
and is based on information from the Sky Report
of Abrams Planetarium, Department
of Physics & Astronomy at Michigan State University, and Hal Kibbey
of the Indiana University Office of Communications & Marketing.
Thanks
are extended for their cooperation.
