Bakersfield Night Sky – October 7, 2017
By Nick Strobel
One of the challenges in writing this column is choosing which astronomy news to write about from the many cool astronomy news stories arriving in my inbox every week. Unfortunately, you’re stuck with my preferences. For this column my preferences for Mars and black holes come to the fore.
In a news release from last week was an early analysis of the effect of the powerful solar eruption on September 11 on Mars as seen by the MAVEN orbiter and the Curiosity rover on the surface. The blast from the sun reached Mars about two days later and created a global aurora more than 25 times brighter in the ultraviolet than any seen before. An aurora on Mars covers the entire planet instead of being concentrated near the magnetic poles like on Earth because Mars doesn’t have a strong magnetic field. Due to its smaller size, Mars’s metal core cooled more quickly than Earth’s. As Mars’s core solidified, the global magnetic field disappeared. The loss of that protective magnetic force field left its atmosphere prey to the solar wind and solar eruptions and its atmosphere was whittled away over millions of years.
The Curiosity rover has an instrument that measured the radiation levels on its seven-month journey to Mars and has been steadily monitoring the radiation environment on the surface of Mars for the past five years. The blast from the sun produced radiation levels on the surface more than double any previously measured and those high readings lasted more than two days. Our thick atmosphere and substantial magnetic field protect us from all that nasty radiation but human Mars explorers are going to have to keep close tabs on the outbursts from the sun. They will have two types of weather forecasts to read about at breakfast: martian weather and space weather.
In another news release about Mars last week was about the possibility of more ice near the Martian equator than originally thought. New data processing techniques on old data from the Mars Odyssey spacecraft still orbiting Mars have increased the spatial resolution by a factor of two. That means it made the old observations twice as sharp.
The new analysis shows that there are concentrations of water ice closer to the equator where conditions would be less harsh for human Mars explorers than higher latitudes. The more water we find on Mars, the less water we have to bring from Earth for human exploration. Besides using the water for our biological needs, the water can be broken apart to produce the oxygen we need to breathe and the hydrogen can be used as fuel.
Now for two black holes news stories. The first black holes story is about a possible way to create the supermassive black holes (ones that are millions to billions of times more massive than stars) we see at the centers of most galaxies. One major mystery in the field of supermassive black hole research is how to form the very big ones we see in galaxies when the universe was very young.
The two possible ways to make supermassive black holes each have their shortcomings. The first way involves multiple mergers of ever larger black holes. However, when you run through the calculations of how many mergers it would take to build up a supermassive black hole in the short time periods we see, the rate is unreasonably high.
Another proposed method for making supermassive black holes involves the direct collapse of huge gas clouds into huge black holes “seeds”. The problem with that method is how to avoid the collapsing gas cloud fragmenting to form stars. A new set of computer simulations shows that supersonic flows when the universe was still a hot plasma soup in the first few hundred thousand years after the Big Bang could do the trick. The dark matter would have clumped more than the ordinary matter in that early universe to form the seeds of big black holes. The ordinary matter would have flowed into those dark matter clumps instead of forming stars. The search is on to see if we can find proof of these black hole seeds.
The second black hole story is about the detection of gravitational waves from the merger of two large black holes of mass 31 and 25 times the sun into a single black hole 53 times the mass of the sun. The math is correct because three solar masses were radiated away in the form of spacetime ripples. Although gravitational waves have been detected before, this detection was the first one by THREE detectors and the first one by the Virgo detector in Europe. The earlier detections were made by the two LIGO detectors in the U.S.
Having three detectors enabled us to more accurately determine the location of the merger to ten times better than the previous observations. The black holes involved in all of the gravitational wave detections so far are several times heavier than ordinary stellar mass black holes.
In two weeks will be the showing of the popular “Black Holes” show at the William M Thomas Planetarium on October 19. Toward the end of that show we see what it would look like inside the supermassive black hole at the center of our home galaxy. Tickets are available from the BC Ticket Office and online from Vallitix.
What's up in the evening and early pre-dawn morning are shown in the star charts below. At 9 p.m. the waning gibbous moon will be just beginning to rise in the east. By that time, Saturn may be getting lost in the muck of our dirty air close to the horizon (see the first chart below). It and the brighter part of Sagittarius called the "Teapot" will be lost in the glare of Bakersfield's light pollution. The Summer Triangle will be high overhead. Early risers will be able to see Venus and Mars low in the east just before sunrise (see the second chart below).
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com