February 2014 Sky from the Keeble Observatory “There’s nothing new under the Sun!” Perhaps that is a truism, though regular readers of this column are used to reports of new discoveries in astronomy and physics. Another trite bit of folk wisdom is the observation that “the more things change, the more they stay the same.” Science isn’t well suited to discovering true novelties. Often the most excitement comes from a discovery that confirms or fills out an existing theory or model (e.g. the Higgs Boson).
Every once in a while Nature throws a surprise at us. The robotic explorer known as Opportunity has been puttering around the Martian surface for almost 10 years. Researchers have drilled into rocks and analyzed data and taken pictures which confirm that the Red Planet was once warmer and wetter than it is today. Those weren’t surprises – it was designed to test for that, and that’s what it found. We expected to find something like those results, building on results from previous probes going back to the 1970s.
Then the surprise. Last month the rover sent an image of a rocky outcropping near its current winter location. 12 days later it returned another image of the same spot … and it showed a rock that wasn’t in the first picture. Not only that, but the new rock looks amazingly like a jelly doughnut! See the before and after images here:
http://apod.nasa.gov/apod/ap140129.html When I first saw this I thought it was an artifact of the lighting angle, since there’s a depression in the earlier image which looks to be similar in shape and orientation. But you can still see that depression in the second picture. The color differences are apparently real, with the outer part of this “new” rock very much whiter than the surrounding surface, and the center somewhat more reddish. Powdered sugar and strawberry jelly? No – the red stuff is very high in sulfur and magnesium, and the rock has twice as much manganese as any Martian rock yet analyzed. Chief investigator Steven Squires said of the mystery rock, “We’re completely confused. We’re having a wonderful time. Everybody on the team is arguing and fighting.”
So how did it get there? Two possibilities have been discussed, and neither has won universal approval. It could have been caught in one of the rover wheels and then flicked into view as Opportunity maneuvered around its winter haven. It could be secondary ejecta from a meteorite strike on the Martian surface. One of my former students has his own suggestion (yell at him for the stereotype!): the space cops dropped it. Isn’t science fun?
Lunar phases for February: No New Moon this month - there were two in January, and there will be two in March; First Quarter on the 6th, at 2:23 pm; Full Moon on the 14th, at 6:54 pm; Last Quarter on the 22nd, at 12:16 pm.
Pre-dawn planet watchers will have a good month. Venus starts the month low to the east before dawn, but climbing higher as we move through February. It will be the brightest “star” above the eastern horizon until the Sun wins the contest. Saturn starts the month in morning twilight almost due south, about 35 degrees above the horizon. Mars is above and to the right, about 40 degrees from the southwest horizon. Interestingly, they won’t appear to move much through the month relative to the Sun’s position because sunrise is beginning to move earlier. They are actually further east relative to the background stars.
Evening finds Jupiter emerging from twilight to the east, about 45 degrees above the horizon. It will appear higher in the sky as the month advances, finishing at about 70 degrees and to the southeast. Mars rises around midnight early in the month, followed two hours later by Saturn. By the end of February Mars will be rising around 10:00 pm.
Our mid-month overhead view finds zenith itself empty of bright stars, but close by to the east you can see Castor and Pollux in Gemini making a nice triangle with Jupiter. Castor is the higher star in the pair, about 10 degrees from zenith, with Pollux about 5 degrees below. To the northwest you’ll find Capella, the brightest star in Auriga about 20 degrees below zenith.
Winter is the best time for seeing Orion, which dominates the southern sky. The red star on the upper right is Betelgeuse, a red giant which would fill our solar system out beyond the orbit of Mars. Below and to the left you’ll see Sirius, the brightest star visible from Earth other than the Sun. Sirius is actually a binary. Sirius A is the primary, about two times the mass of the Sun and intrinsically about thirty times as luminous. Sirius B is a white dwarf with about the same mass as the Sun (but roughly the size of Earth!). A white dwarf is the remnant core of a star which has evolved off the “main sequence” and eventually ejected its outer envelope of hydrogen and helium. Initially it would have been much more massive than Sirius A, and the “planetary nebula” phase must have happened millions of years ago since we see no remnant gas cloud. Sirius appears so bright because of its intrinsic luminosity and relatively near location, a mere 8.6 light years away.
The Pleiades cluster lies above and to the right of Orion, in the constellation Taurus. This cluster is about 400 light years distant, and we can calculate its age as around 10 million years. About 30 degrees to the left of the Pleiades you’ll find the star known as Algol – sometimes nicknamed “the Demon Star.” Algol is an eclipsing binary – the stars alternately pass in front and behind one another as their orbital plane is roughly along the line of sight from Earth. Interestingly, this system was shown to actually contain a third star in 1957 by Dr. Alan Meltzer – who was my undergraduate advisor! His report of the discovery may sound familiar to Latin students and classics majors. He wrote that “Algol is divided into three parts.”Ifreaders have questions about astronomy or science in general that you would like covered in one of these columns, please feel free to contact me at email@example.com.Copyright 2014George Spagna