November 19, 2023
Sunday, November 19, 2023
The two giant planets of the solar system, Jupiter and Saturn, continue to reign in the evening sky. At sunset, Saturn is already at its highest point in the south as it travels across the sky among the dim stars of Aquarius. The moon is at first quarter tonight, about a fist width to the lower right of Saturn. The following night, the moon will be slightly over half a fist width to the lower left of Saturn.
Super-bright Jupiter is already above the eastern horizon at sunset, so it will be the first star-like object you’ll see after sunset. Jupiter is in the constellation of Aries but it’s closer to the head of Cetus. A bright waxing gibbous moon will be slightly less than half a fist width to the right of Jupiter the night of November 24. Two days later, November 26, the full moon will skirt just below the Pleiades star cluster at the shoulder of Taurus, the bull.
Jupiter blazes in the evening while Venus shines even brighter in the morning sky. Venus will be the “morning star” visible in the east by about 3:45 a.m. among the stars of Virgo. At 4 a.m. tonight, Venus and Jupiter will be at the same altitude but on opposite sides of the sky. On the morning of November 29, Venus will have moved close enough to Virgo’s brightest star, Spica, for both of them to fit within the same field of view of your binoculars. Venus won’t be next to another bright star until the first week of January.
In astronomy research news, the Euclid spacecraft recently sent back some spectacular infrared pictures of galaxies, globular clusters, and dark nebulae. Using a 1.2-meter diameter mirror telescope, Euclid was built by the European Space Agency to survey more than one billion galaxies over about one-third of the sky in a mega-data effort to figure out the nature of dark energy. Dark energy is a form of energy of empty space that makes up about 68% of the total universe's energy. It is responsible for making the expansion of the universe increase at a faster rate than before against the attractive force of gravity from dark matter and regular matter that would tend to slow the expansion rate down.
Euclid is going to measure the distortions of light from the galaxies caused by clumps of dark matter as well as very precisely measure their distances to create the most accurate map of the 3D distribution of galaxies in the universe. Euclid’s goal is to distinguish between three possible explanations for the dark energy. Unfortunately, the three explanations create very subtle differences in what we’d see in the past universe, so we need extremely precise and accurate measurements that can only be made in space and we need A LOT of measurements to get good enough statistics, i.e., understand how much of what we see is a true effect vs. the normal random fluctuations that happen with any process in nature.
To make the precise measurements for over a billion galaxies with something like the Hubble Space Telescope or the James Webb Space Telescope would take many decades but Euclid is going to do it over a six-year period. Euclid can do this because it has a very large field of view—about twice the angular size of the moon, or about 100 times wider than what Webb can see (think of a bucket diameter vs. a drinking straw diameter). Euclid’s mirror is much smaller than the large ground-based telescopes but its vantage point in space will mean it has at least four times sharper view than what a ground-based survey could do.
One image in Euclid’s first sample is of the nearby Perseus Cluster of galaxies, 240 million light years away. A thousand galaxies in the Perseus Cluster are seen in two filamentary strands that are perpendicular to each other, following the thin strands of dark matter that make up the “cosmic web” structure of our universe. The structure is easy to see with such a wide field of view. Over 100,000 more distant galaxies are seen beyond the Perseus Cluster, many of which are billions of light years away.
Another image shows the Horsehead Nebula just 1500 light years away in our home galaxy, the Milky Way. This image illustrates that Euclid will also be used to look for newly-formed large exoplanets, brown dwarfs, and baby stars in the Milky Way. The three other images released—spiral galaxy IC 342 (11 Mly away), dwarf irregular galaxy NGC 6822 (1.6 Mly away), and globular cluster NGC 6397 (7800 ly away)—span the distance scale between the Perseus Cluster plus distant galaxies and the nearby Horsehead Nebula star formation region. Learn more about Euclid at the European Space Agency website.
The fall season of shows at the William M Thomas Planetarium will end with the double showing of the traditional holiday show, “Season of Light” on November 30 and December 7. See the Planetarium’s new website for more information about the show and purchasing tickets.
Wishing you a Happy Thanksgiving!
—
Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
