Astro-Images | Rings-Galaxies-Lobes

Follow the astro-images tab above to see previous posts including this how-to.


NGC 3132

Found in the Vela constellation of the southern hemisphere, the Southern Ring Nebula is about 2000 light years from Earth. This nebula is one of many caused by the end stages of stars very much like our Sun. These stars exhaust their supply of hydrogen and helium as they fuse those into heavier elements. The radiant energy of the reactions pushes their outer boundary resulting in a large red giant stage. Our sun will grow to envelope the Earth as a red giant in about 4 billion years.

Gradually the star shrinks under the pull of gravity as the supply of hydrogen and helium runs out in the core. The outer layers of gases surround the star core. Eventually the core collapses triggering an explosion of energy. The outer layers of gases are scattered around the core. The core collapses to about the size of Earth with a mass of about a sun. It is a very small, hot, dense object radiating energetic ultraviolet light at temperatures exceeding 100,000˚C. It causes the surrounding gases to glow in various colors seen in images.

In the center of this nebula are two stars very close together. Click for detail. The very small one is the remaining hot dense core that caused this nebula display. The larger star of the two is younger and will eventually make a nebula.

NGC3132

From original grayscales | Hubble Legacy Archive | J. Ruebush

 

NGC 3314

This is another of the many examples of galaxies that appear to be in collision. But, the near one is tens of millions of light years closer to us than the far one. The alignment makes it appear they are interacting. They are not and won’t in the future.

From original grayscales | Hubble Legacy Archive | J. Ruebush

From original grayscales | Hubble Legacy Archive | J. Ruebush

 

NGC 3372

The letters of the Greek alphabet are used to designate the stars of a constellation or grouping. Alpha, beta, gamma, etc. are the names from brightest to dimmest. I introduce you to Eta Carinae, the seventh brightest in Carina of the southern skies. It is about 100 times the mass of our Sun. It became extremely bright 150 years ago. It was almost as a supernova. But it survived and settled down. Surrounding the star are now two huge lobes of dust in a nebula shaped like a homunculus. It is likely to erupt any time into another spectacular display. Astronomers are watching closely.

NGC3372

From original grayscales | Hubble Legacy Archive | J. Ruebush

 

Venus-Mars | 2015 Conjunction

Early in February I suggested you watch bright Venus in the evening sky as it passed very close to Mars in a beautiful conjunction. Venus came within a lunar diameter of Mars on February 21st. For those fortunate to have clear skies, you could watch from night to night as the event played out. Here in Iowa we had a mix of clouds, some clear days, and some single digit temperatures with wind. That is typical winter weather for the midwest.

I hoped for clear skies so I could photograph the pairing each evening and then combine them into one image showing the movements of each planet. Nature cooperated some of the time.

Overall Perspective

This graphic from an online orrery shows the locations of the planets on February 17th. In this oblique view, each planet is moving counter-clockwise around the Sun. Venus moves faster than Mars and passes it by from the point of view of Earth. I suggest you visit the website and play with it. Advance the days and see how each planet moves.

 

This 30 sec video will give you a good sense of how the two planets were moving relative to each other from the point of view of the Earth. Slower Mars moved almost horizontally to the right each day. Faster Venus moved much more and upward, away from the Sun. I recorded my desktop planetarium software as it advanced the scene one day at a time starting February 17th until the 25th. Notice at mid-video the Moon was also in the tight grouping. It was cloudy for me that day. I missed it.

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Bald Eagles | Then There Were Two

Originally posted on Our View From Iowa:

We are happy to report today that there are two eggs in the Decorah Eagles nest. This video is less than 2 minutes long. Dad shows up. Mom and dad vocalize. Mom leaves for a break. Dad settles in for his turn at keeping the eggs warm and safe.

They have their own Facebook page. Or, follow them live 24/7 at this Ustream site.

View original

Astro-Images | Dwarfs-Eskimos-Collisions

Three examples of the combination of red, green, and blue filtered grayscale images into one of color using the technique I described previously.


NGC 2440

When a star similar to our sun reaches the end of its life, it blows off the material near the surface in a colorful “last hurrah” nebula. The grayscale images I used for this picture were taken on Feb. 6, 2007, by the Hubble Space Telescope. See their color image. The outer layers of gas had formed a cocoon around the star core. Ultraviolet light from the star now makes the debris glow. Different colors indicate elements of hydrogen, helium, oxygen, nitrogen, etc. The white dot burned-out star in the center is called a white dwarf. Our sun will do the same in about 5 billion years. Follow this link to a short video describing the location in Puppis southeast of Sirius and Orion. Click images to embiggen.

NGC2440

From original grayscales | Hubble Legacy Archive | J. Ruebush

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Sea Ice | Loss North – Gain South | Total?

The reports from studies of the extent of sea ice in the polar regions show opposite trends. The north Arctic region is losing areal coverage. The south Antarctic region is gaining areal coverage of sea ice. I discussed these two opposite trends in this recent post. The question many people have is whether this is a bad thing or not. Doesn’t the gain in the south cancel out the loss in the north so it comes out equal?

Claire Parkinson is in her fourth decade of studying polar sea ice. She often got that question from audiences after her presentations. She examined data from 1979 thru 2013 and charted the results below. It is clear the Arctic sea ice losses are profound in the first graph. Also clear is the trend of increases in the Antarctic sea ice in the second graph. That increase is not as large as the losses, however. The third graph shows the Combined data and the overall global decrease. More details of this story can be found at this link at NASA Earth Observatory.

Earth has been shedding sea ice at an average annual rate of 35,000 square kilometers (13,500 square miles) since 1979—the equivalent of losing an area of sea ice larger than the state of Maryland every year.

Earth Observatory | Joshua Stevens | Maria-Jose Viñas | Mike Carlowicz

References and Related Reading

 

Saturn’s Icy Moons | Then and Now

The twin Voyager spacecraft went by Saturn in the early 80s and imaged several moons. During the recent 10 years, Cassini has orbited Saturn and imaged the same moons many times with greater coverage and detail. Here is the link to a web page from Jet Propulsion Laboratory that shows the level of detail before and after of those mission images. This screenshot below is also linked to their web page. You must visit their web page to view the images.

Click to visit the site

Click to visit the site