Bakersfield Night Sky — June 16, 2024
Tonight (June 16) the waxing gibbous moon will be about a couple of knuckles at arm’s length to the left of the bright star, Spica, on the east (left) side of Virgo. Spica is actually a binary system with both stars much hotter than the sun and orbiting each other at about one-third the distance between Mercury and the sun. The stars are so close to each other that their gravity stretches them into ovals pointed at each other. The temperatures of both stars is so high that they emit most of their energy in the ultraviolet, so to our eyes, they appear blue-white.
Three nights later, on June 19, the moon will be the same angular distance to the right of the brightest star of Scorpius, orange-red Antares. Antares is a supergiant star near the end of its lifetime. Antares emits most of its energy in the infrared because it is much cooler than the sun. Despite its cooler temperature, it is emits tens of thousands of times more energy than the sun because it is so large—if placed in the solar system at the sun’s position, it would swallow up all of the planets out to Mars and most of the asteroid belt beyond Mars’ orbit. Antares is one of those stars that could explode as a supernova anytime within the next million years. We’re about 550 light years away from Antares, so we’re in no danger when it explodes but the large distance does mean that it could have already exploded and the light from the supernova hasn’t reached us yet. Antares actually has a companion star orbiting it at almost 14 times farther than Pluto is from the sun. Remember from my previous column about Voyager, that star systems are thousands of times farther apart from each other than Pluto is from the sun, so Antares and its companion are orbiting each other.
The moon will be at full phase the night of June 20. It will be in the thirteenth zodiac constellation, Ophiuchus. June 20 is also the June solstice, marking the day of the longest daylight for the northern hemisphere as well as the official start to our season of summer. On the night of June 27, the waning gibbous moon will be visible in the pre-dawn morning sky to the right of the ringed planet Saturn, about 2 knuckles at arm’s length separates them. That also means that both will appear in the same field of view of your binoculars. The following night the moon will be at third (last) quarter phase.
Earlier this month NASA launched the second of a pair of small CubeSats (each about the size of a shoebox) that will focus their attention on how much solar energy the northern Arctic and southern Antarctic regions absorb and emit back to space. The CubeSats are called PREFIRE for “Polar Radiant Energy in the Far-InfraRed Experiment”. The polar regions emit much of the heat absorbed by Earth at the equatorial regions back out to space mostly in the far infrared wavelengths.
Clouds and water vapor affect how well that far infrared energy leaks back out to space. The two PREFIRE CubeSats are the first satellites to focus their attention on the polar regions, filling in a gap of the measurements input into our climate and ice models. Much of the uncertainty in the climate model projections is due to our uncertainty in how the polar regions are responding to warming global temperatures.
PREFIRE will take at least ten months of measurements to better understand how the energy balance changes over time. The Arctic region is heating up about three times faster than the rest of the planet and ice plays a significant role in keeping Earth’s temperature comfortable for humans since ice reflects about 95 percent of the sunlight hitting it while liquid water absorbs about 95 percent of the sunlight energy. At the other end of the planet, Antarctica’s ice sheets are losing mass at an average rate of 150 billion tons per year.
The more energy Earth absorbs from the sun, the warmer the planet gets. The temperature difference between the colder polar regions and the warmer tropical regions is what drives the global weather system. Plese visit the NASA PREFIRE webpage to learn more.
A few weeks ago, two research teams published their independent discoveries of an exoplanet that might be the closest Earth-like world yet. Both groups using TESS (Transiting Exoplanet Survey Satellite) found an exoplanet orbiting within the habitable zone of the nearby star Gliese 12 (group 1's paper and group 2's paper). Followup observations using CHEOPS (CHaracterizing ExOPlanets Satellite) and several large ground-based telescopes confirmed its existence. The star Gliese 12 is just 40 light years away and the planet orbits the red dwarf star every 12.76 days. Although the derived orbit of the exoplanet Gliese 12b is much smaller than Mercury’s orbit around the sun, the star Gliese 12 is only about half as hot as the sun and emits just three-quarters of one percent of the sun’s energy. Therefore, Gliese 12b is thought to be a comfortable 42 deg C (107.6 deg F). Well, a “comfortable” Bakersfield summer, that is.
Unlike the exoplanets around the equally close star TRAPPIST 1, Gliese 12b probably has an atmosphere around it, protecting possible life on its surface. TRAPPIST 1 is a very active star producing over 100 times more X-rays than does Gliese 12. That means Gliese 12b’s atmosphere hasn’t been blasted away by the star and the exoplanet is close enough to us that the Webb Space Telescope will be able to get detailed spectra of its atmosphere to reveal its composition. More to come!
—
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
