Bakersfield Night Sky — June 21, 2025
In today’s pre-dawn morning sky, a thin waning crescent moon is to the upper right of super-bright Venus low in the east. Over the next couple of mornings, the crescent moon will get even thinner as it slides by the Pleiades cluster at the shoulder of Taurus in the east-northeast. Looking a bit to the right, towards east-southeast, you’ll see Saturn to the lower right of the Great Square of Pegasus. Saturn will be the brightest object you see in that part of the sky. The moon will be at new moon phase on Wednesday, June 25, so we’ll see it climbing up from the western horizon in the last few evenings of June.
On the evening of June 26, a very thin waxing crescent moon will be to the right of Mercury that is making its best evening showing for the current block of evening appearances low in the west, shortly after sunset. Mercury and the moon will be less than a fist width at arm’s length apart from each other, so they should easily fit within the same field of view of your binoculars. In a rough line to the right of the Mercury-moon pair will be Pollux and Castor (in that order) at the heads of the Gemini twins. On the evening of June 29 a bit fatter crescent moon will be almost on top of Mars. Locations in South America will see the moon cover up Mars.
In early June, NASA released a nicely-produced documentary about the James Webb Space Telescope called “Cosmic Dawn: the Untold Story of the James Webb Space Telescope”. The documentary follows Webb from the early design/dreaming stage to its delicate assembly, rigorous testing (and testing and testing), and launch from French Guiana on Christmas 2021. It covers the science behind what we want to do with Webb and the brilliant ingenuity of thousands of smart people working together to achieve those science goals. Although the science is really cool, I probably enjoy even more the parts that highlight the teamwork of passionate people working towards a positive goal. You can watch “Cosmic Dawn” on NASA+ or on YouTube. Go to www.nasa.gov/cosmicdawn/ for the links to your favorite platform.
One of the recent results from the Webb (among many!) is the observation of a young planetary system called “YSES-1” about 326 light years away. The name comes from the “Young Suns Exoplanet Survey” (YSES) being done by the Very Large Telescope in Chile. The YSES-1 system has a young Sun-like star only 16 million years old (our sun is almost 290 times older) with two large, Jupiter-size planets orbiting it at a distance several times farther out than Neptune orbits our sun.
While ground-based telescopes tell us that the exoplanets are still forming, Webb is able to directly study the exoplanets themselves in the mid-infrared wavelengths, peering through the dust in the system that blocks our view from ground-based visible light telescopes. Exoplanet YSES-1b is embedded in a disk of dusty material and exoplanet YSES-1c has clouds of silicate particles in its atmosphere.
YSES-1c is about six times the mass of Jupiter and still glows hot from its formation. One surprising thing is that it still has those clouds of silicates despite it having temperatures of around 1250 to 1520 degrees Fahrenheit—100 to 360 degrees above the threshold temperature that the clouds should disappear.
YSES-1b is at half the distance from the star as its sibling and is a bit larger with about 14 times Jupiter’s mass. YSES-1b is still actively forming as the material from the dusty circumplanetary disk spirals into the planet. YSES-1b is much hotter at between 2420 and 3180 degrees Fahrenheit. The disk seems to contain many very small dust grains that might include olivine, a mineral that has not been previously seen in circumplantary disks. The fine dust particles were expected to have grown into larger particles by now, so finding them still present about three times longer than the expected time period is surprising. Perhaps, the fine grains result from baby moons and planetesimals colliding in the disk. Further work on this system and others in the Young Suns Exoplanet Survey may not happen because of the cuts in federal grants that fund the early-career researchers who do the bulk of the observations and analysis.
The William M Thomas Planetarium is closed for the summer break at Bakersfield College. I hope you’ll be able to enjoy a truly-dark sky filled with stars!
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Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
