Bakersfield Night Sky — October 19, 2024
The Europa Clipper spacecraft is now on its way to explore Europa, a moon of Jupiter slightly smaller than our moon but with big possibilities for currently existing life below its icy surface. Jupiter and its moon system is over five times farther out from the sun than we are and the Europa Clipper is the largest spacecraft NASA ever built for planetary exploration (over 700 kilograms more massive than Cassini), so even a rocket as large as the SpaceX Falcon Heavy can’t fling the spacecraft directly out towards Jupiter against the strong gravitational pull of the sun.
Europa Clipper is going to use the “gravity assist” technique to pick up the speed it needs to climb up away from the sun. Europa Clipper will swing by Mars in four months and then come back to the more massive Earth to get a bigger boost outward in 2026. After traveling 1.8 billion miles, the spacecraft will finally enter Jupiter orbit in April 2030. The Europa Clipper’s orbit around Jupiter will be a huge looping one that makes only brief forays into the harsh radiation environment of Jupiter’s magnetosphere to scan Europa and determine how habitable it is. Europa Clipper does not have the capability to determine if life does exist in the deep ocean below Europa’s icy surface. That would require probes into the deep ocean but we must first determine if the environment is suitable for life and how thick is the ice layer at the surface. The current mission plan is for nearly 50 flybys of Europa in a three-year period but if the electronics and funding last, there could be mission extensions allowing more flybys.
I hope you’ve had the chance to see Comet Tsuchinshan-ATLAS (C/2023 A3) in the evening sky. Pictures by friends on Facebook show the value of dark, clean skies to view it. It passed closest to the sun on September 27 at a distance of just outside the orbit of Mercury. It passed closest to Earth on October 12 at a distance of 44 million miles. Comet Tsuchinshan-ATLAS is now on its outward bound leg of its journey back to the Oort Cloud from where it came. Actually, it may eventually leave the solar system entirely. Its original orbit had a period of over 80,000 years but the gravitational influences of the planets and sun seem to have changed its orbit from a very elongated ellipse to a hyperbolic orbit. Tonight (October 19) it is almost 55 million miles from us. Look for it in the west after sunset among the stars of Ophiuchus (see the attached star chart).
Although the tails can stretch for several million miles, all of the material is coming from a small body six to eight miles across along its longest dimension. The dirty iceberg of rock, dust, and ice is too small for its gravity to crush it down to the most compact shape of a sphere, so it is very likely “potato-shaped”.
The moon was full last Wednesday night and it’ll be at last (third) quarter the night of October 23. That means it will be a bright waning gibbous when the Orionid meteor shower peaks on the night of October 20/21. The Orionids are the result of Earth passing through the dust trail left behind by Comet Halley. The tiny comet dust bits hit our upper atmosphere at 41 miles per second (147,600 mph) and burn up. Because of the waning gibbous moon at the peak of the Orionids, only the brightest streaks will be visible.
“Black Holes” is showing at the William M Thomas Planetarium this Thursday, October 24 and tickets will go on sale for the next two shows, “Incoming!” and “Moon Base” on Friday, October 25.
—
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com
