June 19, 2022
Sunday, June 19, 2022
The season of summer officially begins with the June solstice on June 21 at 2:14 AM Pacific Daylight Time. The sun reaches its northernmost trek among the stars at that time. June 21 will be our day with the longest length of daylight, so we say it's the longest “day” of the year, even though a day is actually a full spin of Earth that includes a time of night. The sun's energy will hit Kern County at its most direct, steepest angle on this day. However, the hottest days of summer will be later in the summer because it takes a bit of time for land and water to warm up.
Earlier this month, the planetary lineup in the pre-dawn morning was a bit more compact with all of the naked eye planets (Mercury, Venus, Mars, Jupiter, and Saturn) grouped within about 90 degrees (half the sky). On Friday, June 24, the two ends marked by Mercury and Saturn will be a bit farther apart but on Friday morning Mercury will be much easier to see than it was at the beginning of the month AND the waning crescent moon will be positioned halfway between Venus and Mars to create a visually beautiful display in our sky. Looking east, from left to right (and lowest to highest in the sky), you'll see Mercury, Venus, moon, Mars, Jupiter, and Saturn.
Tonight, the moon will be a waning gibbous to the right of Jupiter. On the night of June 20/21, the moon will be at third (last) quarter. It will be at new phase on June 28.
On Mars, the Perseverance team may soon have to say goodbye to the Ingenuity helicopter as Ingenuity's solar panels accumulate too much dust and the night time temperatures drop significantly below the threshold of the electronics design. Ingenuity has lasted FAR longer than its design specifications, so all of its work for the past several months has been bonus.
Mars always has very fine dust in its atmosphere and much of it is magnetic, so it sticks to metallic surfaces as it settles out, including the solar panels on Ingenuity and the InSight lander at a different location on Mars. Ingenuity and Perseverance are exploring Jezero Crater which is a dustier place than Elysium Planitia where InSight is operating. On average four dust devils pass by Perseverance every sol (martian day) and the surface conditions are such that it's easier for dust to get lifted up into the air at Jezero Crater than at other places we've explored with rovers and landers.
Jezero Crater is now going into the season of winter, so the lower daytime temperatures and shorter daylight means that Ingenuity cannot store enough energy for the cold night (down to -112 deg F so far) to keep itself warm. Ingenuity now shuts off during the night and reboots in the morning. Eventually, the electronics will give out. One of its sensors, the inclinometer, that it uses in getting itself ready for take off has stopped working. The Ingenuity team has figured out a workaround to get the data needed for taking off safely and programmed a software patch. Hopefully, the patch will work and Ingenuity can have a few more flights. Perseverance is nuclear-powered, so it'll be able to survive the winter just fine. Its older cousin, Curiosity in Gale Crater, is also nuclear-powered and it's still functioning after over 3500 sols.
In other astronomy news here on Earth, India has opened a new eye on the sky with its unique International Liquid Mirror Telescope (IMLT) at the 2450-meter (8038-foot) Devasthal Observatory in the Himalayas. The liquid mirror is made of 50 liters of mercury in a four-meter diameter circular container that spins to create the parabolic shape necessary to gather and focus light to a point.
Such a telescope is over nine times cheaper to make than one with a glass mirror but it's not steerable, so it looks straight up and relies on Earth's spin to bring a new patch of sky into view. Objects appear as long streaks but the separate pixels can be added together with software to create a single long exposure. Exposures over multiple nights can be added together to create images of very faint objects or one night's image can be subtracted from the next night's image to find out what changed such as a supernova burst or a quasar flare-up. Right next door to the IMLT is the 3.6-meter Devasthal Optical Telescope (DOT) that uses the normal glass mirror design. DOT will be used to follow-up on any transient objects that IMLT finds.
The IMLT will be the test platform for technology that could be used for giant telescopes on the moon. Liquid mirror telescopes on the moon won't use mercury, though, because of the too-large expense of transporting the mercury to the moon and mercury would freeze during the night and vaporize during the day. Instead, so called “ionic liquids” made of lightweight molten salts with low melting points could work on the moon. A thin coat of silver could make the surface reflective. There's a proposal for a 100-meter liquid mirror telescope at one of the moon's poles.
I hope you'll be able to go out and enjoy a truly dark sky filled with stars sometime this summer!
—
Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
