October 15, 2023
Sunday, October 15, 2023
This Thursday evening, October 19, the William M Thomas Planetarium will present the ever-popular “Black Holes” show. The doors open at 7 p.m. and are locked when the show begins at 7:30 p.m. The Black Holes show describes the two basic types of black holes: the stellar-mass ones that form when very massive stars die and the supermassive monsters at the centers of most galaxies, including our own Milky Way galaxy.
The supermassive black holes at galaxy centers have millions to billions of times the mass of a typical star and we aren’t sure how they get so big. If they form from the mergers of stellar-mass black holes, the merger rate seems incredibly high—unreasonably/implausibly high because we find very young galaxies from shortly after the start of the expansion of the universe (the Big Bang) with supermassive black holes that are already hundreds of millions to even billions of times the mass of a typical star. How did they get that size so quickly and what then slowed down the growth rate?
We have had indirect evidence of streams of gas connecting the galaxies to each other, so those gas streams could be feeding the beasts at the galaxy cores. Recently, astronomers using the Keck Telescope on Mauna Kea, Hawaii have developed techniques to directly image these filaments of gas that string galaxies together in a cosmic web. The James Webb Space Telescope has been able to image galaxies even closer to the Big Bang than can the Hubble Space Telescope and we’ve seen that galaxies of large size can develop much quicker than expected. We have a lot more to learn about galaxy formation! New eyes on the cosmos reveal new mysteries to untangle—physical reality is always more interesting than the virtual reality we imagine.
The supermassive black hole at the center of the Milky Way is comparably quite small, just 4 (or so) million times the mass of the sun. The one in our closest large neighbor, the Andromeda Galaxy is several hundred million times the mass of the sun. The Black Holes show will take you right inside the Milky Way’s central black hole using the equations of General Relativity.
Next month, the two shows will be “From Earth to the Universe” (on November 2) and “Dynamic Earth” (on November 16). See the Planetarium’s new website for more information about the shows and purchasing tickets.
Last Wednesday, October 11, the OSIRIS-REx (asteroid sample return mission) team let us know what they were able to collect from asteroid Bennu. Based on just the stuff that had leaked out of the sampler, we see that Bennu has an abundance of hydrated clay minerals (clay fibers with water locked inside the crystal structure, showing that there was a lot of water in the early solar system), sulfide mineral plates, iron oxide “framboids” and “plaquettes” that help catalyze biochemical reactions. Carbon makes up 4.7% of the material, making the Bennu sample the highest percentage of carbon in any extra-terrestrial sample measured so far. The sample is loaded with organic globules (organic means molecules of carbon bonded with hydrogen).
The Psyche spacecraft was scheduled to launch on October 13, to study the asteroid, Psyche, that is thought to be an exposed metal core of an earlier larger asteroid. Large objects would have formed with enough heat to liquify their interiors that, in turn, enabled dense material like iron and nickel to sink to the center while the lighter stuff such as silicate rocks and carbonate materials floated upward, creating a differentiated interior.
The Psyche spacecraft is also going to test out NASA’s Deep Space Optical Communications (DSOC) that will use lasers instead of radio waves to transmit information. Since lasers use light of much shorter wavelengths than those of radio waves, a lot more information can be transmitted in a given time interval with lasers. The expected data rate gain should be 10 to 100 times the capacity of radio systems.
The drawback is that the transmitters-receivers must be more carefully aligned than with radio systems, so the first generation DSOC will be useful out to “only” 240 million miles or just the first two years of Psyche’s outward bound journey to the asteroid. The alignment precision will need to be as good as hitting a dime from a mile away while the dime is moving. Easy, right?
Yesterday was the new moon with a solar eclipse, so tonight’s moon will be an extremely thin waxing crescent visible for just a short time after sunset low in the southwest. Monday evening’s view will be easier to see. The Orionid meteor shower peaks on the night of October 21/22 but with a broad peak, the nights before and after the peak should be almost as good. The Orionids are the result of Earth plowing through Comet Halley’s dust trail and the comet bits hit the upper atmosphere at 41 miles/second. As they burn up tens of miles above the ground, they make the brief streaks of light that appear to originate from a radiant located in the upper left part of Orion. The moon will be at first quarter phase on the night of the peak, so it should be setting as Orion is getting up to a decent altitude. On the night of October 28/29, the full moon will be right next to bright Jupiter.
Wishing you dark skies!
Nick Strobel
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
