Saturday: The Perseid meteor shower peaks next week. But there will be an increased number of meteors over the next two weeks. If the Moon is out when you want to look, position yourself so you are in the Moon’s shadow. The meteors appear to come from a point just below the W of the constellation Cassiopeia. This point is about two and a half fists held upright and at arm’s length above the northeast horizon at 11 p.m. By dawn, this point is about seven fists above the northeast horizon. If you fall asleep or forget to set your alarm, you will be able to observe this shower from about 11 p.m. to dawn for the next two weeks in about the same location in the sky. The Perseid shower is one of the longest lasting showers. For tips about optimizing your viewing this year, go tohttps://earthsky.org/?p=165416 As your Mother might say, dress warm and sit in a comfortable chair for maximum enjoyment. These meteors are sand to pea-sized bits of rock that fell off of Comet Swift-Tuttle. They are traveling about 40 miles per second as they collide with the Earth and burn up in the atmosphere.
Sunday: Saturn is in opposition tonight. That doesn’t mean
that Saturn is stubborn. Opposition means that Saturn is on the opposite side
of the Earth as the Sun. When an object is in opposition, it is at its highest
point in the sky during the darkest time of the day. Thus, opposition is
typically the best time to observe a planet. Saturn is about two and a half
fists above due south at 1 a.m. It is about one fist above due southeast at 10
p.m. Careful readers of this column should realize they could be doing
something much more interesting. But they also may recall that Saturn is in
opposition on nearly the same date every year: June 14, 2017. June 26, 2018,
July 9, 2019, July 21, 2020. An outer planet is in opposition when Earth passes
it up as both orbit the Sun. The farther out a planet is, the less it has moved
along its orbit, and the closer it is to exactly one year from one Earth passing
to the next. For comparison, it is about 18 months between successive
oppositions for Mars.
Monday: The Moon is right in between two star clusters in
the sky at 4:30 this morning. The Pleiades is less than a fist above the Moon
and the Hyades is less than a fist below the Moon. The Pleiades is a cluster of
about 1,000 stars that is about 400 light years away. The Hyades is a cluster
of about 400 stars that is about 150 light years away.
Tuesday: Venus is a half a fist above the western horizon at
9:15 p.m.
Wednesday: It is not winter yet. But Orion, thought of as a
winter constellation, is just above the east-southeastern horizon at 5:00 a.m.
By the actual winter, it will be visible in the evening sky.
Thursday: Mizar is a well-known binary star in the
constellation Ursa Major. You can find it at the bend in the Big Dipper handle,
four fists above due northwest at 11:00 p.m. Its name is Arabic for waistband.
Mizar has an optical double called Alcor, which is less than a pinky width away
and can easily be seen with the naked eye. Optical doubles are stars that are
close together in the sky but do not orbit a common center of mass as true
binary stars. Not wanting to deceive sky gazers who call Alcor and Mizar a
binary star, two stars that DO orbit a common center of mass, Mizar actually is
a binary. It was the first binary star system discovered using a telescope.
Mizar A and Mizar B are about 400 astronomical units apart from each other and
about 80 light years from Earth. 400 astronomical units is about 10 times the
distance between the Sun and Pluto.
Friday: Jupiter is one and a half fists above due southeast
at 11:00 p.m.
The positional information in this column about stars and
planets is typically accurate for the entire week. For up to date information
about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
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