Saturday: 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 three and a half fists held upright and at arm’s length above due south at 1:00 a.m. It is nearly two fists above due southeast at 10:00 p.m. Careful readers of this column may recall that Saturn is in opposition on nearly the same date every year: July 9, 2019, July 21, 2020, August 1, 2021, August 14, 2022, and August 26, 2023. 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.
Sunday: “You know Aries and Cancer and Draco and Libra. Leo
and Pisces and Virgo and Hydra. But do you recall, the pointiest asterism of
all? Triangulum, the three-sided asterism, had a very pointy shape. And if you
didn’t know it, you would say it poked an ape.” Sorry. Some stores have started
sending out their Christmas catalogs and that has put me in the mood to modify
some Christmas songs. Anyway, Triangulum is a small constellation between the
more prominent Andromeda and Aries. Its main feature is a skinny triangle
oriented parallel to and four fists above the eastern horizon at 11:30 p.m.
Monday: Fomalhaut, the southernmost bright star visible from
the northern USA, is one fist above the south-southeastern horizon at 11:00
p.m. In 2008, Fomalhaut and its surroundings became the first star system with
an extrasolar planet to be directly imaged. See the family photo at https://apod.nasa.gov/apod/ap081114.html.
Tuesday: While many people think they need a telescope to
enjoy looking at the night sky, some objects actually look better through
binoculars. Open star clusters are one of those types of objects. M39, the 39th
object in Charles Messier’s catalog, is straight overhead at 11:00 p.m. This
open star cluster contains about 30 stars in a region that is about seven light
years across and a thousand light years away. A quick trigonometry calculation
shows that the cluster is about the same size as the full moon in the night
sky. Read more about M39 at https://stardate.org/radio/program/2022-09-04.
Wednesday: At 1:00 a.m., Jupiter, the brightest point of
light in the sky at this time, is one and a half fists above the
east-northeastern horizon. Mars is a fist to the lower left of Jupiter.
Thursday: Earlier this week, you read about Fomalhaut, the
second brightest star with a planet. The brightest star known to have a planet
is Pollux, in the constellation Gemini. (First vs. second brightest is
meaningless here because they are nearly identical in magnitude, 1.15 vs.
1.16.) Pollux is four and a half fists above due east at 5:30 a.m., right below
its “twin” star Castor. Read more about Pollux at https://goo.gl/cL5t9p.
Friday: Arcturus is two fists above the western horizon at
9:00 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.
All times are Pacific Time unless noted.
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