Bakersfield Night Sky — April 21, 2024

By Nick Strobel | 04/19/24
Late April at midnight looking east-southeast

We’re now in the home stretch for spring semester at Bakersfield College. Just two weeks to go before we reach final exams week. The William M Thomas Planetarium gave its last evening public show for the spring season with the premier of “Moon Base: The Next Step” last Thursday. The next two weeks will be field trip shows and then the planetarium closes for the summer.

We’re also now near the end of seeing Jupiter in the evening sky for this year. Shortly after sunset tonight, you’ll be able to see it very low in the west but by the end of this week, it may be too low in the sky through the Bakersfield haze. Jupiter will go behind the sun on May 18 and re-appear as a bright star low in the east in the pre-dawn sky in late June. Above Jupiter at about a fist width at arm’s length is the lovely Pleiades star cluster.

Tonight is the peak of the Lyrid meteor shower as Earth moves through the dust trail left behind by Comet Thatcher (C/1861 G1). The comet dust particles will hit our atmosphere at 30 miles/second. The Lyrids can sometimes produce fireballs and fireballs might be the only thing you can see from the Lyrids this year because of the bright waxing gibbous moon that is 96% lit up. The Lyrid meteor shower gets its name from the radiant’s location on the west (right) side of the constellation Lyra. The radiant is the point in the sky from where the meteors appear to come.

Tomorrow the moon will be right next to the bright star Spica of Virgo. They’ll be just a pinky-width apart but Spica is bright enough that you should still be able to see it next to the nearly full moon. The moon is at full phase on the night of April 23.

In the pre-dawn sky, look to the east to find Mars and Saturn on the east (left) side of Aquarius. Mars is to the left of Saturn about three knuckles of a clenched fist apart held at arm’s length and growing farther apart each night. By the end of the month, they’ll be about a fist and a half apart from each other.

About a year-and-a-half ago in October 2022 a very bright burst of gamma rays reached Earth. This gamma ray burst (GRB 221009A) was thought to be the result of the core collapse of a massive, rapidly-spinning star to form a black hole while the outer layers were blasted to space in a supernova explosion. The black hole has an accretion disk of hot gas spiraling into it. Such an object is called a “collapsar”. This explanation was confirmed when a team led by Peter Blanchard pointed the James Webb Space Telescope at the site of the gamma ray burst. They waited until six months after the collapse to point Webb at the object in order to allow enough time for the expanding shell of material to spread out enough to reveal the disk of material spiraling into the black hole.

Supernovae are thought to be one significant way that elements heavier than iron are created in the universe. One of the major discoveries in astronomy is that most of the atoms that make up us and the rest of Earth were originally created long ago and far away in the cores of dying stars and then dispersed into other gas clouds in the dying throes of the large stars. The atoms produced in this stage of a star’s life include atoms of carbon, oxygen, etc. on up to iron. Atoms heavier than iron (such as gold, platinum, and uranium) are produced in the much rarer extreme events of supernovae, collapsars, and collision of neutron stars.

While observations have shown the presence of the heavy elements in supernovae and merging neutron stars, an earlier study of fainter gamma ray bursts creating collapsars found a lack of heavy elements. Blanchard’s team’s JWST observations seem to show that we should scratch collapsars as a source of the heavy elements because they also found no heavy elements even with this brightest of all gamma ray burst events. The potential problem with this is that the other sources do not come close to producing enough of the heavy elements to account for what we do measure in the universe. We hoped that collapsars would fill the deficit.  Although the sample size is admittedly too small to rule out collapsars as a source of the heavy elements, it may be time to re-examine our accounting of the heavy element sources.

Nick Strobel

Director of the William M Thomas Planetarium at Bakersfield College

Author of the award-winning website