Bakersfield Night Sky – May 21, 2016
By Nick Strobel
Last Friday over 600 BC students walked across the stage at the 2016 commencement as family members, friends, faculty, and staff cheered them on. This week a large group of faculty are preparing for the next academic year learning about the Guided Pathways program that will make it possible for many hundreds of more students to get their degrees in less time and cross that stage than 2016's graduates. More about that in a future article.
On the Monday of finals week, we managed to get a glimpse of Mercury transiting the sun as the sun peeked out briefly from behind the clouds. By the last hour of the eclipse, the sky had cleared up a lot more, so I was able to see the black dot of Mercury with the Planetarium's solar scope as I proctored the final exam. I posted a few pictures from the Mercury transit on the William M Thomas Planetarium's website at www.bakersfieldcollege.edu/planetarium . Included in the set is a comparison of the Mercury transit with the Venus transit of 2012. Venus appears about seven times larger because it is closer to the Earth and it is 2.5 times the diameter of Mercury.
The next transit of Mercury will be November 11, 2019. It will be another early morning one for us, already in progress as the Sun rises. After that we'll have to wait until November 13, 2032 for another Mercury transit. Venus transits are much rarer. We'll have to wait until December 11, 2117!
The Kepler planet-hunting team released a huge addition to the exoplanet catalog, almost 1300 new exoplanets found using the transit technique. The transit technique can find large and small planets from the slight dimming of a star when the exoplanet passes directly between us and the star. Small exoplanets make a very small dip in the starlight, so Kepler's photometer is exquisitely precise. Imagine a high-rise hotel with 1000 rooms and they all have their lights on. If just one of the window blinds is lowered by less than two inches, Kepler would be able to detect the change in brightness.
Nearly 550 of the new exoplanets are small rocky worlds and nine of them orbit in their host star's habitable zone. That brings to 21 exoplanets that are small worlds like the Earth residing in the habitable zone of their star. We have found plenty of larger worlds in the habitable zones of their stars.
In 2018, the Transiting Exoplanet Survey Satellite will use the same transit technique to look for exoplanets orbiting 200,000 bright nearby stars. For four years, Kepler kept its gaze fixed on a section of the sky in the wing part of the constellation Cygnus. When Kepler's pointing system wore out, NASA was able to retask the satellite to monitor stars along the direction of the ecliptic plane which is the plane of the planets in our solar system.
Kepler's ultra-precise photometer can be used for tasks other than planet-hunting. A day after the huge addition to the exoplanet catalog was announced, another research team announced that the dwarf planet with the catalog number 2007 OR10 is significantly larger than previously thought. At 955 miles in diameter, 2007 OR10 (can we please give it a name already?) is the third largest dwarf planet in our solar system. Only Pluto and Eris are larger. 2007 OR10 is quite dark and it is currently twice as far from the sun as Pluto in its very elliptical orbit. Its dark red surface is probably due to ices of methane, carbon monoxide and nitrogen covering its surface.
The research team used Kepler's photometer to measure 2007 OR10's rotation speed together with infrared observations from the now-defunct Herschel satellite to constrain size estimates and how reflective 2007 OR10 is. More details about the Kepler results are available on the Kepler website at kepler.nasa.gov.
In our night sky, Jupiter reigns supreme high in the south as the sky gets dark enough to see the rest of the stars. Jupiter is now moving in its regular eastward drift below the back end of Leo. Jupiter will set at about 2:30 am. Mars is now rising at about sunset and getting up highest due south at midnight. As we pass by Mars in our inside faster orbit, Mars is appearing to move backward, or retrograde, among the stars of Scorpius. We will be at closest distance to Mars on May 30 at a mere 46.8 million miles from Earth and we'll see Mars in Libra.
The Curiosity rover has now completed two martian years and NASA/JPL released the weather report from the past two martian years. Temperatures in Gale Crater have ranged between a high of 60.5 deg F on a summer afternoon to minus 148 deg F on a winter night but average monthly values are between 30 deg F in the summer and minus 130 deg F in the winter with day-night swings of about 100 deg F due to Mars's very thin atmosphere. See mars.nasa.gov for more details.
Fifty minutes behind Mars will be Saturn. Look for it to the left of the red heart of Scorpius, the supergiant Antares.
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