Centaurus-A is located in the southern hemisphere skies. I have never seen it from my location 42˚ north latitude. It rises only 5˚ above my southern horizon in early December. I’m certain it is very familiar to my blogger friend Roger in Australia. It is the 5th brightest galaxy and easily viewed by amateurs. It contains a black hole of 55 million solar masses ejecting jets of x-ray and radio wavelengths. Models suggest the galaxy collided with another smaller galaxy in the past leading to areas of star formation in the resulting complex structure. I enjoyed combining 3 greyscale Hubble images into this composite. In the center are several newly formed bluish stars. The dark areas are dust blocking the passage of light.
What will the Moon look like on any date in 2020? What will it look like on your birthday? Find out at NASA Dial-a-Moon. Go here to see views for northern hemisphere and for southern hemisphere readers. Scan down that web page for much additional information about the Moon’s motions and appearance.
Enter any month and day to see a high definition image. The composite images of Dial-a-Moon are made from those of the Lunar Reconnaissance Orbiter (LRO) in low altitude orbit around the Moon since 2009.
You may leave the universal time (UT) at the default value. If you wish, your local-to-Universal time conversion can be done at this link. Or, type ‘universal time’ into Google. Go back to Dial-a-Moon to enter the UT.
The star Betelgeuse has been in the news since December 2019. It is called a Red Giant due to its color and size. It is the upper left shoulder of Orion seen in this chart from Wikipedia Commons.
Orion_constellation_map.png: Torsten Bronger
It has a slight reddish hue visually and a diameter estimated to be nearly as large as the orbit of Jupiter. Betelgeuse is a variable star meaning its brightness changes over time. The time period is quite long on the order of 2000 days. In December 2019, variable star observers reported it had rapidly reached its lowest level ever observed. Speculation is widespread over whether it will soon become a Supernova. More on that later.
The astronomy community has reported a confusing phenomenon in recent years that the universe is composed of mostly matter and energy we don’t understand and cannot see. The terms dark matter and dark energy are used to describe these unknowns. I posted earlier about their confusing nature. The normal matter we can see and measure comprises only about 5% of the universe. The remaining 95% is ‘dark’ to us. Not dark in the sense of absence of light. We are unable to see it in the same ways we detect ordinary matter. The distribution is depicted here by Chandra X-Ray Observatory.
Progress is being made toward the detection and better understanding of the distribution of dark matter and dark energy. The progress uses techniques which infer the presence of something invisible which affects the visible normal matter. Techniques such as gravitational lensing are used. Theories are tested to see if observations match predictions. Progress is slow and difficult.
There are some very smart people working on this puzzle. Two of them are a wife-husband team who work at the Jet Propulsion Lab JPL in California. Alina Kiessling and Jason Rhodes are Astrophysicists with NASA-JPL. On 17 October 2019 they presented the public talk linked below for JPL’s Theodore von Kármán Lecture Series. It was one of the best programs on this topic I have seen.
In their program, they explained aspects of dark matter and energy, how it is detected, and what might be the ultimate fate of the universe. All was done in a manner that was not technical or overwhelming and included entertaining and humorous examples. At the end they answered audience questions.
I watched the 7 hour spacewalk and was impressed by the amount of work, the quality of the jobs done, and how difficult it was. Here is the follow-up news conference by NASA astronauts Christina Koch and Jessica Meir. If you have contact with young women at home or in the classroom, share with them.