Bakersfield Night Sky – June 20, 2015
By Nick Strobel
Tomorrow marks the official start of summer with the June solstice, although we have definitely been experiencing summer weather already. On our sky, the Sun has been moving steadily northward, so the length of daylight has been increasing. On the solstice, the Sun "stands still" before beginning to drift southward for the rest of summer and fall. During our spring and summer, the northern hemisphere is tipped toward the Sun, concentrating the Sun's energy on our part of the Earth. Greater cooking power and greater cooking time, means it bakes in Bakersfield.
The Earth has also been moving farther away from the Sun during the spring and first part of summer. Yes, farther away. The hotter temperatures are due to the angle of the sunlight, not the distance we are from the Sun. We'll be farthest from the Sun, at "aphelion" on July 6th.
Next Saturday, June 27th, is the free public star party hosted by the Kern Astronomical Society at Panorama Park from 8 to 10 PM at Panorama Park near where Linden Ave runs into Panorama Drive. The Moon and planets, including Saturn, will be bright targets to see along with beautiful star clusters and nebulae. Observing will start soon after sunset and go to about 10 PM, depending on foot traffic.
On the night of the free public star party, the two brightest planets, Jupiter and Venus, will be about two knuckles at arms length apart from each other in the western sky. At the end of the month, they'll be less than a thumb width apart from each other. Saturn will also be a "must-see" in the southeastern sky. The positions of all three planets are shown in the attached star chart. Tonight, a Waxing Crescent Moon will be a bit left of the Jupiter-Venus pair. In the middle of the week, the Moon will be at First Quarter so it'll look like half of it is lit up by the Sun. It will be among the stars of Virgo. By the time of the free public star party, the Moon will be a very bright Waxing Gibbous phase on the right (west) side of Libra. Saturn will be nearby on the left side of Libra but it will be bright enough to spot even with the glare of the Moon.
I have been keeping track of Pluto's ever-sharpening face as New Horizons speeds toward its July 14th flyby of the Pluto-Charon double (dwarf) planet system and its tumbling small moons. By the time it flies by Pluto-Charon, New Horizons will have journeyed over 3 billion miles. Although, the flyby will be July 14th, New Horizons won't beam any data back until the following day and thereafter because it will be too busy madly snapping pictures and taking data as it flies by at 31,300 mph. After its July 14th encounter, the New Horizons team hopes to fly by another Kuiper Belt object even further out. It will depend on the health of the spacecraft and the health of the funding stream from NASA.
For the past month or so, we have been able to view various parts of Pluto's surface as it rotates every 6.4 Earth days. That is also how long it takes Pluto and Charon to orbit around their common center of mass, so the two worlds are gravitationally locked to keeping the same face towards each other. The New Horizons team has combined the images to make a movie of Pluto spinning that you can check out on the New Horizons website at http://pluto.jhuapl.edu . We can see very dark and very bright terrain in the equatorial region and what appears to be a polar cap.
On the New Horizons homepage is an inspiring movie called "The Year of Pluto" that describes the discovery of Pluto in 1930 by Clyde Tombaugh, the speculations about that tiny pinprick of light in the following decades, the discovery of its large moon Charon in 1978 that enabled us to accurately measure the small size and mass of Pluto, and the work by hundreds of people led by Alan Stern to make New Horizons a reality.
Launched on the nation's fastest rocket on January 19, 2006, New Horizons took just nine hours to cross the orbit of the Moon. It got a gravity boost from Jupiter in late February 2007 that shaved six years off its journey to Pluto. It's hard to believe that finally, 85 years after its discovery, we're going to see it up close!
Closer to home, the Dawn spacecraft continues to beam back fantastic images of the dwarf planet Ceres and all sorts of spectrographic data telling us what Ceres is made of. In my previous column I said that the bright spots in a large crater 55 miles across are likely exposed ice but another possibility is salt. We haven't seen bright spots in this configuration before, so they have definitely sparked a lot of interest in what they could be.
The Dawn team is still taking your vote of what the bright spots could be on their "What's the spot on World Ceres" page at www.jpl.nasa.gov/dawn/world_ceres . Choices includes volcano (with water as the lava), geyser, rock, ice, salt deposit, and "other".
The other deep-space mission, Rosetta to the Comet 67P/Churyumov-Gerasimenko, had one especially good piece of news last Sunday. The Philae lander awoke from its seven-month hibernation to briefly speak with the Rosetta orbiter. The comet has now moved to Mars' distance from the Sun. With that comes greater heat and sunlight energy to warm up the lander in its hiding place. Hopefully, it will be able to get enough solar energy to fully charge its batteries and tell us more about the comet from the ground level. More updates posted at http://rosetta.esa.int .
One last piece of astronomy news is that we may now be watching the beginnings of a planetary nebula form. A planetary nebula is puffing out of the outer layers of a dying star like our Sun will do about 7 billion years from now. Low-mass stars like our Sun do not explode in a supernova but, instead, have a gentler death. Many stars will puff their outer layers out of their poles to create beautiful hourglass-like structures that can look like a butterfly if we see them edge-on.
Up to now we haven't known how these bi-polar planetary nebula were formed because we have seen just the end result. The star L2 Puppis, 210 light years away, may help us solve the puzzle. The two most popular ideas involve a companion star that creates a disk of dust (made of tiny grains of olivine and pyroxene) and gas around the dying star's equator, constraining the outflow to move perpendicular to the disk in the polar directions. The theories differ on how the equatorial disk is formed.
Using an "extreme adaptive optics" in the visible band with the European Southern Observatory's Very Large Telescope, a team of astronomers has confirmed the presence of a companion star and what looks like the earliest stages of a bipolar planetary nebula. The nebula is now only about the size of Uranus' orbit but over the following centuries, it will grow to many thousands of times the size of Pluto's orbit.
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