Saturday: Jupiter is one and a half fists held upright and at arm’s length above the east-southeastern horizon and Saturn is about two fists above the south-southeastern horizon at 9:00 p.m. Jupiter is the much brighter of the two. When you are looking at this part of the sky, you are looking in the direction of more than just the two planets. You are also looking in the direction of their moons. Titan, Saturn’s largest moon, is easily visible with a small telescope, about six “ring diameters” to the side of Saturn at this time. Jupiter’s four largest moons are also visible with a small telescope. Callisto, Ganymede, and Io are one one side of Jupiter, with Callisto appearing the farthest away, Ganymede in the middle, and Io closest. Europa is visible in the other. Last year, a team of Canadian astronomers analyzed images of Jupiter from 2010 and estimated that Jupiter could have 600 moons at least 800 meters, a half mile, in diameter. They didn’t actually discover these moons. They just formulated a possible model of the Jovian system. For more on this, go to https://skyandtelescope.org/astronomy-news/jupiter-could-have-600-moons/.
Sunday: Two years ago, astronomers announced that they
detected phosphine, a possible biosignature of life, in the upper atmosphere of
Venus. Although the surface of Venus is inhospitable, astronomers have long
speculated that the upper atmosphere could harbor life. Not Cloud City life
from The Empire Strikes Back but maybe microbial life. Last year, astronomers
concluded that the original scientists found the signature of sulfur dioxide,
not life. Last month, the private company Rocket Lab published details about
the first privately funded mission to another planet - their trip to Venus,
scheduled to launch as soon as May 2023. This Venus storyline is an excellent
example of science at work. In less than two years, science went from “we may
have found a marker for life on Venus” to “it is unclear if we found a marker
for life” to “we probably didn’t find a marker for life” to “let’s visit Venus
to closely study the thing we thought was a marker for life”. Do an internet
search of the words venus and phosphine and read the articles to follow the
story. To get yourself in the mood, go outside at 6:15 a.m. Venus is just above
the eastern horizon at this time.
Monday: The bright star Vega is about five fists above the
western horizon at 11:00 p.m. Its fellow Summer Triangle star Deneb is about
two fists above it. Altair, the third star in the triangle, is about four fists
above due southwest.
Tuesday: The bright star Capella is two fists above due
northeast at 11:00 p.m.
Wednesday: The Beehive Cluster is less than a half a fist to
the lower right of the waning crescent Moon at 5:00 a.m. They are about three fists
above due east.
Thursday: At 6:06 p.m. PDT, the center of the Sun crosses
the celestial equator and passes into the southern sky. The celestial equator
is an imaginary line that divides the sky into a northern and southern half.
When the Sun is in the southern half of the sky, it appears to take a shorter
path from rising to setting. It also does not get as high in the sky at noon.
This leads to shorter days and longer nights. Since the Sun crosses the
celestial equator today, there is an instant when it is equally in the northern
and southern sky, called the north and south celestial hemispheres. This
so-called “equal night” is given by the Latin word equinox. Thus, today is
known as the Autumnal Equinox. However, the day and night are not of equal duration
today. The sun rises at 6:49 a.m. and sets at 6:59 p.m. in the northern
latitudes of the United States. At these latitudes, day and night are closest
to equal duration on Sunday.
Friday: The bright star Sirius is two fists above the
south-southeastern horizon at 6:00 a.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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