Saturday: 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.
Sunday: The moon, Venus, and the star Spica form a small
triangle just above the west-southwestern horizon at 7:45 p.m. Venus appears
about 100 times brighter than Spica. Both are above the moon.
Today is an even better day to see a planet during the day.
Wait until the sun is low in the western sky so its light is less intense - try
7:00 p.m. Next, find the moon with your naked eye. Then aim your binoculars at
the moon. Look for Venus to the upper left of the moon, about one binocular
field of view away. Finally, lower the binoculars and look at that same spot
with your naked eye. Venus should be visible.
Monday: “There’s water in them thar craters,” frozen water,
that is. There has been speculation since the 1960s and indirect evidence since
the 2000s of water on the Moon. Three years ago, astronomers studied data from
four earlier missions. They noticed that the light reflecting off the bottom of
craters near the lunar South Pole showed characteristics of light reflecting
off pure ice. The water likely came from comet impacts or other solar system
objects with trace amounts of water ice. Last summer, the Indian Space Research
Organization became the fourth country to successfully land on the moon when
Chandrayaan-3 landed near the lunar South Pole to study the water there. Read
more about it at https://www.space.com/chandrayaan-3-moon-south-pole-why-nasa-wants-to-go-too.
Tuesday: Saturn is two fists above the east-southeastern
horizon at 10:00 p.m.
Wednesday: Fomalhaut, the farthest south of all the bright
stars visible in the northern United States, is one fist above the
south-southeastern horizon at 11:00 p.m.
Thursday: Mnemonics are helpful for remembering astronomy
facts. (Similarly, “Johnny Mnemonic”, the 1995 cyberpunk film, was helpful in
getting Keanu Reeves’ career going.) After all, school children around the
world are learning the order of the planets by remembering, “My very excellent
mother just served us nine….” Oops, I guess that one needs updating with Pluto
being classified as a dwarf planet. Well, here’s one that will not need
updating for tens of thousands of years: the order of the stars in the Big
Dipper. Because the nighttime stars are so far away from us, their actual
motion through the sky, called their “proper motion” is not noticeable over
even thousands of years. That is why the constellations have remained the same
since ancient times. But two stars in the Big Dipper have a proper motion large
enough such that in 100,000 years; the stars will no longer make a dipper
shape. You can see this simulation at the American Museum of Natural History
video found at https://youtu.be/sBfUBtdo8yo.
Until then, you can remember the names of the seven dipper stars in order from
handle to cup by remembering this helpful advice for teens: “AM, ask mom. PM,
dad.” The stars are Alkaid, Mizar, Alioth, Megrez, Phad, Merek, and Duhbe. The
Big Dipper is about one fist above the northern horizon at midnight.
Friday: At 6:00 a.m., Jupiter is two and a half fists above
the eastern horizon. Mars is four and a half fists above the eastern horizon,
two fists to the upper right of Jupiter.
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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