April 3, 2022
Sunday, April 3, 2022
Tickets are on sale for the showing of “MARS One Thousand One” at the William M Thomas Planetarium that will be presented on April 21 at 7:30 PM While it's no longer required to be masked indoors at BC, with the vaccination rate at just 54% in Kern County, you may consider wearing a mask inside the closed space of the Planetarium, especially if you have or are living with someone with a compromised immune system. Doors open at 7 PM for general admission seating and are locked at 7:30 PM when the show begins. Go to the Planetarium's website at bakersfieldcollege.edu/community/planetarium to get the links for buying tickets online and more information about the show.
The fine-alignment of the James Webb Space Telescope mirrors and calibration of the instruments continues according to plan. There is a seven-stage process getting the mirrors all exquisitely aligned and sending the infrared light to all four instruments. The first stage looked at the bright nearby star HD 84406 when the Near Infrared Camera cooled below 120 Kelvin (approximately -244 degrees Fahrenheit). The 18 mirrors produced 18 fuzzy images of the star as expected. The second stage moved the secondary mirror which is on a tripod in front of the large primary. The secondary mirror redirects the light back to a center hole in the primary mirror. The science instruments are behind the primary mirror. The secondary mirror was moved slightly in the second stage to see the effect on the 18 fuzzy images.
The third stage was image stacking where the 18 mirrors are aligned to put all of the individual images on top of each other. The fourth stage had three rounds of Coarse Phasing and a final round of Final Phasing where the alignment is fine-tuned to a position accuracy smaller than the wavelength of the infrared light (much smaller than a hair width). The fifth stage was fine phasing at the center of the NIRCam's field of view. This stage produced the brilliant star image you've probably seen on the internet. It's a pretty engineering image but not any science information will come from this. It was an exposure of 2100 seconds at about 2 microns wavelength (human eyes can see wavelengths between 0.4 microns for violet and 0.7 microns for red).
The sixth stage is now in process. The super-precise alignment is extended to the other three science instruments (NIRSpec, MIRI, and the FGS-NIRISS that I described in a January column) and across their entire field of view. The seventh and final stage is the final correction in the alignment which should be finished at the end of April/first of May. Then we'll able to create images in infrared colors and measure compositions, densities, speeds, temperatures, etc. from infrared spectroscopy. I'm hoping that the first beautiful science images will be posted by BC's Commencement on May 12. We'll be back in person AND in the stadium!
Early morning risers have had a much prettier display of the planets than evening sky watchers. Venus, Mars, and Saturn have been close together in the southeast before dawn. Venus is pulling away from the two outer planets and Mars and Saturn have been getting closer together. On the morning of April 5, Mars and Saturn will be less than one Moon diameter apart on our sky. Both will be about the same brightness. Mars will be the lower reddish one of the two. A small telescope should be able to pick out the rings of Saturn.
On the pre-dawn morning of April 18, you'll be able to see four planets equally spaced in a line in the east-southeast. Jupiter will be at the far lower left, then Venus, then Mars and then finally Saturn at the upper right end. Jupiter and Venus will blaze brighter than any other star in the sky with Venus the brightest of all. (By the way, there may be future NASA missions to Venus because new research is showing that Venus could have had a significant amount of liquid water in the past before it became so hellishly hot from a runaway greenhouse effect—more about that in a future column.) Mars and Saturn will be as bright as the brighter stars in the sky.
In the evening of early April, we'll have to be content with a thickening waxing crescent moon moving through the constellation of Taurus. Tomorrow night, it will be next to the Pleiades star cluster at the shoulder of Taurus. On April 6, the moon will be a fatter crescent between the horns of Taurus. First quarter is on the evening of April 8 and full moon is April 16. I hope you'll be able to enjoy a truly dark sky filled with stars sometime this month!
—
Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
