The fall semester is about to begin. The K-12 schools start this week and Bakersfield College starts Aug. 23. One of my classes will be taught on campus with a simultaneous Zoom. Masks are required for on-campus classes and vaccinations will be encouraged, but I’m a bit nervous about how the delta coronavirus variant will affect our on-campus classes this fall.
I’m not nervous about the current evening sky, though. It’s going to be great with bright planets visible in the evening. Venus is the brilliant “evening star” visible in the west after sunset. It will be the first starlike object you see after the sun sets. About a couple of fist widths at arm’s length (or one hand width with fingers outstretched) left of Venus is the bright true star Spica in Virgo.
In the south, you’ll see the waxing gibbous moon just one day past first-quarter phase. Continuing left is the bright orange-red star at the heart of Scorpius, Antares, a supergiant so large that if it were centered in our solar system, it would swallow up all of the planets out to about Jupiter.
Rising in the southeast, you’ll see the two giants of our solar system, Saturn and Jupiter to the left of Saturn. Saturn is in the middle of the constellation Capricornus and it has been putting on a particularly good show the past couple of weeks. At opposition, when Saturn is 180 degrees opposite the sun in our sky, the rings get particularly bright from sunlight backscattering off the ring particles back to us on Earth.
Although Saturn is now far enough away from opposition, the rings are tilted at a very aesthetically pleasing angle that is sure to wow anyone who looks at it through a telescope.
By the way, the backscattering off the moon’s soil is why the full moon is so much significantly brighter than the day before or after full phase. (Backscatter is the reflection of waves back to the direction from which they came.) The moon will be at full phase on Saturday night.
Even though Saturn has those gorgeous reflective rings, Jupiter is over 17 times brighter because Jupiter is larger and closer to us. Overall, they both reflect the same percentage of sunlight that hits them, but Jupiter is only 5.2 times farther out from the sun than Earth, while Saturn is 9.5 times farther out from the sun. Jupiter will be at opposition on Thursday night. Both Jupiter and Saturn are undergoing retrograde motion, drifting backward toward the west among the stars as Earth passes them by in our inner faster orbit.
If you traced an arc from Jupiter to Saturn to Antares to the moon to Spica to Venus, you’d trace the ecliptic arc, which is the projection of Earth’s orbit onto the sky. I have it indicated in the accompanying star chart.
Much closer to the western horizon are Mars and Mercury, but they’re so close to the sun in our sky that they’re lost in the twilight glow (and probably hidden behind a smoke layer from the wildfires).
CHALLENGES ON MARS
The Perseverance rover’s first attempt at collecting a sample was unsuccessful. The percussive drill with its hollow coring bit did its job and the sample tube was processed correctly, but it looks like the sample tube is empty. The Martian rock target did not react in the way expected, so Mars is showing us once again that it’s a planet different than Earth.
In 2008, the Phoenix mission team had to work with some surprisingly viscous soil, taking several attempts before they got the soil into that lander’s onboard instruments. Curiosity has had some difficult drillings with rocks that turned out to be harder and more brittle than expected. The heat probe on the Mars InSight lander was unable to penetrate into the ground as planned.
Jennifer Trosper, project manager for Perseverance at JPL/NASA in Pasadena, said that she has “been on every Mars rover mission since the beginning, and this planet is always teaching us what we don’t know about it. One thing I’ve found is, it’s not unusual to have complications during complex, first-time activities.”
I’m sure the team will figure out what’s going on because they have extremely bright people working together without egos getting in the way.
Contributing columnist Nick Strobel is director of the William M. Thomas Planetarium at Bakersfield College and author of the award-winning website AstronomyNotes.com.
