Bakersfield Night Sky - December 5, 2021
Bakersfield Night Sky — December 5, 2021
By Nick Strobel
Lunar eclipses and solar eclipses usually go together (though two weeks apart). Two weeks ago (on the night of November 18/19) was a nearly total lunar eclipse. Yesterday was a total solar eclipse but there wasn't much hype about it in the media since the path of totality was over the Southern Ocean and a small section of Antarctica. The new moon was just two hours from perigee—closest orbit point to Earth—so the moon was moving fastest sideways on the sky. Earth is also getting close to perihelion—closest orbit point to Sun—so the sun appears slightly larger on our sky than at other times of the year. Put both of those things together and yesterday's total solar eclipse was at best slightly less than two minutes long.
The next total solar eclipse will be the April 2024 eclipse going through the middle of the U.S. and northern Mexico and a small piece of Canada. All of the orbital elements will work together to make that eclipse last up to 4.5 minutes long. The longest total solar eclipse this decade will be the one in August 2027 visible in Spain, northern Africa, Saudi Arabia and Yemen. That will be up to 6.3 minutes long. Yes, they're short but they are truly awesome events that have to be experienced in person—video broadcasts don't do them justice.
The day before Thanksgiving saw the launch of the Double Asteroid Redirection Test (DART) mission that will crash into the small asteroid moon of a larger asteroid sometime between September 26 and October 1 next year. The moonlet, called Dimorphos, is just 530 feet (160 meters) across and it orbits the asteroid Didymos which is 2,560 feet (780 meters) in diameter. Neither asteroid is ever going to hit Earth and the impact of DART into Dimorphos is not going to change that fact. However, the change of Dimorphos' orbit around Didymos will be much easier to measure than if we tried the redirection of a single asteroid's orbit around the sun.
Riding along with the main spacecraft is LICIACube, a CubeSat built by the Italian Space Agency that will separate from the DART shortly before impact to record what happens. Several observatories on Earth will also be watching from a safe distance of 6.8 million miles (11 million km) away. Four years later, the European Space Agency will send the Hera mission to examine the two asteroids up close.
All sorts of computer simulations have been done to predict what will happen when DART rams Dimorphos but we need to test the computer models with an actual experiment. DART is the first Planetary Defense test mission and it's a simple test—how well can we nudge an asteroid?
There are no known asteroids larger than 140 meters in size that will hit Earth in the next 100 years but we have probably found only about half of the estimated 25,000 Near Earth Objects (NEOs) that are 140 meters and larger so far. An asteroid 140 meters in diameter hitting Earth would produce only regional effects while something 300 meters across would effect a continent or two and a one-kilometer object would have a global effect (mass extinctions everywhere). The Vera Rubin Observatory that will go online next year was expected to find a bunch more NEOs but the deployment of the constellations of tens of thousands of communication satellites such as SpaceX's Starlink, OneWeb, and Amazon's Project Kuiper will make that search impossible. Even if we can get the satellite constellations below naked eye visibility, each satellite will still be millions of times brighter than a dark asteroid on its way to Earth.
We've been enjoying the brilliant Venus in our evening sky in the west. Yesterday it was at maximum brilliance. Venus has “rounded the corner” on its orbit as seen from Earth, so it'll now be drawing closer to the sun on our sky as it begins to move in between us and the sun. Tonight Venus will set almost three hours after sunset but by the end of the month it will set just one hour after sunset. In a telescope you'll see Venus become a very thin crescent shape. If you know right where to look low in the southwest, you might be able to see an extremely thin waxing crescent moon but tomorrow will be even prettier sight of a slightly fatter waxing crescent moon just below the brilliant star-like Venus (see the star chat below).
To the left of Venus will be the giant planets Saturn and Jupiter. Jupiter will be the brighter one of the two on the left. Saturn is near the right side of Capricornus and Jupiter is now mid-way between Capricornus and Aquarius. The crescent moon will pass under Saturn on December 7 and Jupiter on December 8. The moon will be at first quarter phase on December 10. On December 18, the moon will be full and this one will be a “micromoon”—full phase near the apogee or farthest point in its orbit around Earth. Since this full moon is the one nearest the winter solstice, the full moon take its farthest north path across the night sky, staying above the horizon for a long time.
Orion becomes visible in the east shortly before 7 PM and it'll be highest in the sky due south at about 12:20 AM The two brightest stars in the dog constellations, Canis Major and Canis Minor, are Sirius and Procyon, respectively. Those stars are first visible at about 8:45 PM
If you're vaccinated, you have a MUCH smaller chance of getting so sick that you need to be hospitalized in Kern's over-crowded hospitals or of getting the long-haul COVID. Hospitals filled with COVID patients can't take in heart attack, stroke, or accident victims. Check out My Turn vaccination information page for the clinic closest to you and please continue wearing a mask when with large groups in enclosed spaces!
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Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
