Bakersfield Night Sky — March 18, 2017
by Nick Strobel
The observing campaign of TRAPPIST-1, the tiny star with seven Earth-sized exoplanets, by NASA’s planet-hunting Kepler Space Telescope finished up the first week of March and the raw data were posted to the web for anyone to process. The 74 days of monitoring of TRAPPIST-1 by Kepler was the longest stretch yet by any observatory. The Kepler data should refine the previous measurements of six of the exoplanets and significantly improve the stats for the seventh exoplanet as well as search for planets that remain undiscovered in the system.
A different team used the Hubble Space Telescope to gather ultraviolet data from TRAPPIST-1 that could give us an idea of the age of the TRAPPIST-1 system and also tell us if the UV levels are high enough to vaporize the atmospheres of the planets. The ultraviolet data seem to show that TRAPPIST-1 is on the young side which means at least 500 million years old for stars like TRAPPIST-1. The UV levels are high enough to strip an Earth-like atmosphere from the two innermost planets but probably not enough to threaten the three exoplanets that are definitely within the habitable zone. Further observations are needed to confirm these tentative findings (and I’m sure the observing time will be easily granted).
The Cassini spacecraft orbiting Saturn in a set of large, looping polar orbits that take it just outside the main rings returned high resolution images of the innermost moon, Pan. The tiny moon, just under 18 miles across, sweeps out a gap about 200 miles wide in Saturn’s A ring called the Encke Gap. Early pictures showed a ridge around Pan’s equator that made it look like a flying saucer. The images returned last week show the ridge has some ripples and the rest of the moon has some scratches. The result looks like a dumpling, empanada, or ravioli.
Two days from now, on the morning of March 20, the sun will cross the Celestial Equator heading northward to mark the beginning of our season of spring. The vernal (spring) equinox will be at 3:29 a.m. PDT. The summer-like temperatures of this past week make it seem that spring already came and went for us though! With the full moon happening last Sunday, that means Easter (and the end of Spring Break in Kern County) is late this year. Easter falls on the Sunday after the first full moon after March 21.
On Thursday, March 23, will be the “Dynamic Earth” show at the William M Thomas Planetarium. Dynamic Earth, narrated by Liam Neeson, explores the inner workings of Earth's climate system. With visualizations based on satellite monitoring data and advanced supercomputer simulations, this cutting-edge production follows a trail of energy that flows from the Sun into the interlocking systems that shape our climate: the atmosphere, oceans, and the biosphere. Tickets are on sale now.
In our evening sky Venus continues its plunge toward the Sun as it heads toward “inferior conjunction”—when it passes between Earth and the sun—on March 25. As Venus descends, Mercury ascends. Tonight they’ll be at about the same altitude above the western horizon as shown in the second chart below. Dimmer Mercury will be to the left of Venus. Mercury will reach its highest altitude in the first week of April. Orange-red Mars is almost three fist-widths above and to the left of both Mercury and Venus tonight and will set about three hours after sunset.
Looking east at about 9:15 p.m. you will see Jupiter rising and shortly afterward, the brightest star of Virgo, Spica, will become visible. Jupiter reaches its highest point at about 2:30 a.m. Jupiter is moving retrograde as we catch up to it in our faster inner orbit. Retrograding Jupiter will move a little further west away from Spica through the rest of this month and April.
The first star chart below shows the southeastern sky at 10 p.m. Jupiter and Spica are at the far left of the chart. Higher up in the southeastern sky is Leo with the distinctive sickle shape or backward question mark at the head and front of the lion. The bright star Regulus is at the bottom of the sickle.
In the south is the brightest star in the night sky, Sirius, at the nose of Canis Major. Although Sirius is quite bright, Jupiter still beats it easily. Slightly higher in the southwest at 10 p.m. you’ll see the belt of Orion. The bright stars Betelgeuse and Bellatrix are above Orion’s belt at Orion’s shoulders (at his right and left shoulders, respectively) and the bright stars Saiph and Rigel are at Orion’s right and left knees, respectively. We will continue to see the winter constellation Orion in our evening sky in the southwest for another month and a half, though it will be harder to see as sunset happens later each evening.
Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com