Bakersfield Night Sky — April 15, 2017
by Nick Strobel
Next Saturday, April 22, the Cassini spacecraft orbiting Saturn will make its closest flyby of Titan since 2010. This very close flyby of Titan (just 615 miles above Titan) will significantly change Cassini’s path to set it up for the Grand Finale Orbits. This final set of orbits will take Cassini high above the poles and then zoom between the rings and the cloud tops.
This final set of orbits will enable us to make detailed maps of Saturn’s gravity and magnetic fields that will reveal the interior structure of Saturn. We’ll also get much better measurements of the amount of material in the rings and those measurements will give us a better understanding of the origins of the rings. Some of the orbits will have Cassini collect some particles from Saturn’s D-ring and, of course, we’ll get awesome, high-resolution images of the rings and clouds.
The final orbit will end on September 15 when Cassini plunges into Saturn. Cassini is running out of fuel and the mission is running out of funding, so we want to end the mission while we still have control of the spacecraft. Having it plunge into Saturn will also prevent Cassini from accidentally crashing into Enceladus and Titan. Those two moon have the raw ingredients for life: an energy source (gravitational flexing from Saturn), organic compounds, and a liquid for the organics to dissolve, mix, and interact. Enceladus has a global ocean of liquid water below its icy crust. Titan has lakes of liquid methane on its surface and a layer of liquid water below is crust. We don’t want to contaminate these worlds with any terrestrial microbes that might have survived the trip from Earth and the thirteen years of exploration of Saturn and its moons.
On April 27, the William M Thomas Planetarium will give its final show of the spring season, the popular “Black Holes”. Tickets are still on sale from the BC Ticket Office and the online Vallitix site. Doors will open at 7 p.m. and the hour-long show begins at 7:30 p.m. with a tour of the evening sky followed by the Black Holes show.
Mercury has disappeared from our evening sky but Jupiter blazes away in the southeast among the stars of Virgo; already up as the sun is setting (see the star chart below). Jupiter will be highest due south shortly after midnight. During the last ten days of this month, you’ll see Mars pass between the two star clusters in Taurus (in the west after sunset): the Pleiades at the bull’s shoulders and the Hyades at its nose. A thin waxing crescent moon will speed by them on April 27 and 28.
In the predawn sky, Saturn is retrograding among the left side of Sagittarius and Venus is now visible as the super-bright star low in the east before sunrise. It will reach its greatest brilliance near the end of the month.
The week before Spring Break I was at a conference about the accreditation commission that accredits the 113 community colleges in California, including Bakersfield College, plus the ones in Hawaii and the Pacific islands, such as Guam, American Samoa, Palau, and Micronesia. Accreditation is a voluntary, peer review process that is unique to American educational institutions. The peer review of accreditation reminded me of the importance of peer review in the process of scientific discovery.
Unlike the echo chambers of our social media and politics today, peer review in the science research arena is a rigorous, critical process where claims are tested and either validated or thrown out. Peer review works best if the ones who critically analyze an explanation have an alternate explanation and try to poke holes in the other person’s explanation. (Sometimes that "poking" is pretty brutal!)
In his book “The Demon-Haunted World”, Carl Sagan noted, “Perhaps the sharpest distinction between science and pseudoscience is that science has a far keener appreciation of human imperfections and fallibility than does pseudoscience.” It is possible to arrive at various interpretations of the same data or facts and to develop various explanations of the underlying causes at work. Our culture, egos, and personal beliefs provide a filter through which we interpret the data and develop explanations.
Decades of psychology and social science research have shown that our perceptions, intuitions, and even the reasoning about our intuition can lead even the best of us astray. That is why scientists lay their results open to the very critical scrutiny of others. And they agree to accept the criticism and re-submit their work when they have improved their argument through better data or give it up when the observations show that their idea does not have merit. They don't blame the “establishment" or make personal attacks.
Finally, the peer review process gives the discovery or explanation credibility and fosters innovation as thoughts are shared and debated in an open competition of ideas. Innovation from a competition of ideas is the key to the past success of the United States. Innovation can’t happen if government bureaucrats and politicians control the review process—that would only solidify the status quo.
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