A Blue Moon Halo over Antarctica : Have you ever seen a halo around the Moon? Such 22 degree rings around the Moon – caused by ice crystals falling in the Earth’s atmosphere – are somewhat rare. OK, but have you ever seen a blue moon? Given the modern definition of blue moon – the second full moon occurring in a calendar month – these are also rare. What is featured above might therefore be considered doubly rare – a halo surrounding a blue moon. The featured image was taken late last month near Zhongshan Station in Antarctica. Visible in the foreground are a power generating house and a snowmobile. What might seem to be stars in the background are actually illuminated snowflakes near the camera. via NASA


The last but not least of Assorted Planets Month!

And now to cool you all off with some “refreshing” rain!

This week’s entry: Planetary Rain

Puppis A Supernova Remnant

(via APOD; Image Credit & Copyright: Don Goldman )

Driven by the explosion of a massive star, supernova remnant Puppis A is blasting into the surrounding interstellar medium about 7,000 light-years away. At that distance, this colorful telescopic field based on broadband and narrowband optical image data is about 60 light-years across. As the supernova remnant expands into its clumpy, non-uniform surroundings, shocked filaments of oxygen atoms glow in green-blue hues. Hydrogen and nitrogen are in red. Light from the initial supernova itself, triggered by the collapse of the massive star’s core, would have reached Earth about 3,700 years ago. The Puppis A remnant is actually seen through outlying emission from the closer but more ancient Vela supernova remnant, near the crowded plane of our Milky Way galaxy. Still glowing across the electromagnetic spectrum Puppis A remains one of the brightest sources in the X-ray sky.

NASA Astronomy Picture of the Day 2015 August 27 

The Large Cloud of Magellan 

The 16th century Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two fuzzy cloud-like objects easily visible to southern hemisphere skygazers are known as the Clouds of Magellan, now understood to be satellite galaxies of our much larger, spiral Milky Way galaxy. About 160,000 light-years distant in the constellation Dorado, the Large Magellanic Cloud (LMC) is seen here in a remarkably deep, colorful, image. Spanning about 15,000 light-years or so, it is the most massive of the Milky Way’s satellite galaxies and is the home of the closest supernova in modern times, SN 1987A. The prominent patch below center is 30 Doradus, also known as the magnificent Tarantula Nebula, is a giant star-forming region about 1,000 light-years across.

Dark Nebula LDN 810

This image was obtained with the wide-field view of the Mosaic camera on the Mayall 4-meter telescope at Kitt Peak National Observatory. LDN 810 is a dark nebula that was first cataloged by B.T. Lynds in 1962. The dark region at the center contains gas and dust out of which new stars are forming. A bipolar outflow of gas from one of these stars has also been detected. A faint trail of dust and gas extends from the center of the image to the upper-left corner. The image was generated with observations in the Us (violet), B (blue), V (green) and I (red) filters. In this image, North is up, East is to the left.

credit line: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF) 



Today Phil follows up last week’s look at the death of low mass stars with white dwarfS. White dwarfs are incredibly hot and dense objects roughly the size of Earth. They can also form planetary nebulae: huge, intricately detailed objects created when the wind blown from the dying stars is lit up by the central white dwarf. They only last a few millennia. The Sun probably won’t form one, but higher mass stars do.

Table of Contents
When low mass stars die they form white dwarfs 0:54
White dwarfs are roughly the size of Earth 2:16
Cloudy with a chance of Planetary Nebulae 3:59
Life Span 9:06

PBS Digital Studios:

Follow Phil on Twitter:

Want to find Crash Course elsewhere on the internet?
Facebook -
Twitter -
Tumblr -
Support CrashCourse on Patreon:

Journey to the centre of the Sun [credit: ESA/Hubble (M. Kornmesser & L. L. Christensen)]
Blowing Bubbles [credit: (NASA/CXC/April Jubett)]
Artist’s impression of the sizes of Sirius B and the Earth [credit: ESA and NASA]
The Dog Star, Sirius A, and its tiny companion [credit: NASA, ESA, H. Bond (STScI), and M. Barstow (University of Leicester)]
The Spirograph Nebula [credit: NASA/ESA and The Hubble Heritage Team STScI/AURA]
M27, NGC6853, Dumbbell Nebula [credit: REU program/NOAO/AURA/NSF]
Soap Bubble Nebula, PN G75.5+1.7 [credit: T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF]
Hubble Sees Supersonic Exhaust From Nebula [credit: Bruce Balick (University of Washington), Vincent Icke (Leiden University, The Netherlands), Garrelt Mellema (Stockholm University), and NASA/ESA]
Hubble snaps NGC 5189 [credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)]
A dying star’s toxic legacy [credit: ESA/Hubble & NASA]
Eskimo Nebula [credit: NASA/Andrew Fruchter (STScI)]
Planetary nebula Abell 39 [credit: WIYN/NOAO/NSF]
The Butterfly Hunter [credit: (NASA/CXC/April Jubett)]
Red Giant Sun (video) [credit: ESA/Hubble (M. Kornmesser & L. L. Christensen)]
The planetary nebula Abell 33 captured using ESO’s Very Large Telescope [credit: ESO, Wikimedia Commons]
ESO’s VLT images the planetary nebula IC 1295 [credit: ESO]
Looking Down a Barrel of Gas at a Doomed Star [credit: The Hubble Heritage Team (AURA/STScI/NASA)]