What is a black hole?

This post comes from NASA's Space Place. NASA's Space Place is a NASA educational website about space, Earth science, and technology.

NASA's Space Place in a SNAP! is a series of quick, narrated tours of animated infographics that illustrate key science concepts. Not only are they fun and entertaining on their own, they also come with a downloadable poster and a transcript of the video, making for a cross-disciplinary learning experience. The latest topic—black holes!

What is a black hole? A black hole is an area of such immense gravity that nothing—not even light—can escape from it. Find out what they are today at http://spaceplace.nasa.gov/black-holes. This post explains black holes in simple non-mathematical language.

Mars Opposition is April 8th.

Approximately once every two years Earth and Mars are relatively close together. The time when the Sun and Mars are directly opposite each other is called opposition. The opposition of Mars will occur on April 8th. On April 14th Earth and Mars will be the closest they will be for this two year cycle.

For these reasons, the month of April will be a particularly good time to observe Mars through a telescope. Normally all you will see is a blurry red disk, but for a few weeks before and a few weeks after opposition, it is possible to see surface detail with a ground based amateur telescope. While Mars can be easily seen with the naked eye at other times, it is brighter and easier to find near opposition.

The article http://earthsky.org/astronomy-essentials/mars-2014-opposition-how-to-see-april-best-time-to-see-brightest has more information.

Confirmation of Cosmic Inflation

In the late 1970's Alan Guth made a proposal: early in the history of the universe, shortly after the big bang, the universe went through a rapid and dramatic expansion. This expansion was so rapid it might be described as an "explosion" or a second big bang, though neither term is quite right. Instead this expansion was given the understated name "inflation."

Inflation caused the universe to expand faster than the speed of light. You might think this violates special relativity. But special relativity does not say that "nothing can travel faster than light" only that ordinary material objects cannot do so. It does not prevent space itself from expanding faster than the speed of light.

Up until recently inflation was purely a theoretical concept, there was no direct experiment evidence to support it. There was indirect evidence. There are observations which were not explained by the standard big bang theory. And these observations are neatly explained by inflation, but do not prove that inflation is true.

Observations made from telescopes near the south pole recently provided more direct evidence for inflation. By detecting gravitational waves from the early universe, scientists have direct evidence for the first time. See this article by Dennis Overbye in the New York Times...

http://www.nytimes.com/2014/03/18/science/space/detection-of-waves-in-space-buttresses-landmark-theory-of-big-bang.html

The size of the solar system.

Many people don't realize how spread out the solar system is. There is a lot of distance between the Earth and other objects like Venus and Mars. Here are two pages which demonstrate this in two different ways...

1) you'll need to scroll to the right to explore. You'll need a lot of scrolling to the right...
http://joshworth.com/dev/pixelspace/pixelspace_solarsystem.html

2) this should be more or less self explanatory...
http://www.youtube.com/watch?v=YE2w_JBGEwk

John Dobson

John Dobson popularized what is now called the "Dobsonian" telescope in the 1950's. He passed away earlier today....

From the Sidewalk astronomer's web site (https://www.facebook.com/Sidewalkastro)

It is with great sadness and heavy hearts that we have to report the passing of Mr John L. Dobson. He died peacefully this morning, January 15th, 2014, in Burbank, California. He was 98. John leaves behind a son, many close friends, and legions of friends, fans, and admirers around the globe.

ISAN 7 (International Sidewalk Astronomy Night) will be held in honor of John on March 8th. Amateur astronomers worldwide can join in and celebrate his life by carrying the torch that John lit back in 1968 when he co-founded the San Francisco Sidewalk Astronomers.

John was a friend and mentor to all who met him. He will be dearly missed.

Update on Comet ISON

Comet ISON has brightened recently. Comets can be unpredictable, so we can't know exactly how bright it will get. But it is worth taking a look.

It will pass behind the sun on November 28th, the best view is likely to be sometime between now and the 28th. If you want to view the comet the following are good resources:

• http://www.isoncampaign.org/
• http://www.isoncampaign.org/karl/did-ison-fragment
• http://isontracker.com/

On November 18, there was information about Comet ISON on spaceweather (http://spaceweather.com/).

'We may be able to watch dark energy turn on': U-M involved in unprecedented sky survey

"Through the Dark Energy Survey, which began Aug. 31, more than 200 researchers from 25 institutions, including U-M, will search for answers to a fundamental question about the cosmos: Why is its expansion speeding up?"

This is a paragraph from the University of Michigan news service article "'We may be able to watch dark energy turn on': U-M involved in unprecedented sky survey." This survey, if successful, may shed light on the nature of the mysterious dark energy.

http://www.ns.umich.edu/new/multimedia/videos/21661-we-may-be-able-to-watch-dark-energy-turn-on-u-m-involved-in-unprecedented-sky-survey