This Photograph Of Neptune Was Reconstructed From Two Images Taken By Voyager 2’s Narrow-angle Camera,

Bright stars of Sagittarius and the center of our Milky Way Galaxy lie just off the wing of a Boeing 747

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Comas and Tails of Comets The generally unexpected and sometimes spectacular appearance of comets have triggered the interest of many people throughout history. A bright comet can easily be seen with the naked eye. Comets are usually not discovered until after a coma or tail has formed. Depending on the apparent size of the coma or tail, a comet can be very bright. Some comets have a tail extending more than 45˚ on the sky. The earliest records of comet observations date to ~6000BCE in China. The smaller nucleus (rocky body) of a comet, often only a few kilometres in diameter, is usually hidden from view by the large coma, a cloud of gas and dust roughly 10 to the power of 4-10 to the power of 5 km in diameter and not seen with the naked eye, a large hydrogen coma, between 1 and 10 million km in extent, which surrounds the nucleus and visible gas/dust coma. Two tails are often visible, both in the antisolar direction: a curved yellowish dust tail and a straight ion tail, usually of a blue colour. Comets are usually inert at large heliocentric distances and only develop a coma and tails when they get closer to the sun. When the sublimating gas evolves off the surface of a comet’s nucleus, dust is dragged along. The gas and dust form a comet’s coma and hide the nucleus from view. Most comets are discovered after the coma has formed when they are bright enough to be seen with relatively small telescopes. ~ JM Image Credit More Info: Comets, NASA Coma

Hoag’s Object Hoag’s Object is a non typical galaxy of a type known as a ring galaxy. It is a nearly perfect ring of hot blue stars which circle around the yellow nucleus of this ring galaxy. The galaxy is approximately 600 million light years away from the constellation Serpens. Image credit: NASA

The little-known nebula IRAS 05437+2502 billows out among the bright stars and dark dust clouds that surround it in this striking image from the Hubble Space Telescope [2001 x 1654]

Spirit sends one of those pictures that looks like it could come from the red rock deserts of the American West, but actually shows part of the landscape in Gusev crater, a mere 60 million miles away. Credit: NASA

The dune field at the center of Victoria Crater, seen in a new false-color shot. Credit: NASA

Remember kids: Pluto is not a planet, WAS never a planet, and any acknowledgement of Pluto as a planet was an error of assumption

Burst of Celestial Fireworks : Like a July 4 fireworks display a young, glittering collection of stars looks like an aerial burst. (via NASA)

Cosmic rays

Cosmic rays provide one of our few direct samples of matter from outside the solar system. They are high energy particles that move through space at nearly the speed of light. Most cosmic rays are atomic nuclei stripped of their atoms with protons (hydrogen nuclei) being the most abundant type but nuclei of elements as heavy as lead have been measured. Within cosmic-rays however we also find other sub-atomic particles like neutrons electrons and neutrinos.

Since cosmic rays are charged – positively charged protons or nuclei, or negatively charged electrons – their paths through space can be deflected by magnetic fields (except for the highest energy cosmic rays). On their journey to Earth, the magnetic fields of the galaxy, the solar system, and the Earth scramble their flight paths so much that we can no longer know exactly where they came from. That means we have to determine where cosmic rays come from by indirect means.

Because cosmic rays carry electric charge, their direction changes as they travel through magnetic fields. By the time the particles reach us, their paths are completely scrambled, as shown by the blue path. We can’t trace them back to their sources. Light travels to us straight from their sources, as shown by the purple path.

One way we learn about cosmic rays is by studying their composition. What are they made of? What fraction are electrons? protons (often referred to as hydrogen nuclei)? helium nuclei? other nuclei from elements on the periodic table? Measuring the quantity of each different element is relatively easy, since the different charges of each nucleus give very different signatures. Harder to measure, but a better fingerprint, is the isotopic composition (nuclei of the same element but with different numbers of neutrons). To tell the isotopes apart involves, in effect, weighing each atomic nucleus that enters the cosmic ray detector.

All of the natural elements in the periodic table are present in cosmic rays. This includes elements lighter than iron, which are produced in stars, and heavier elements that are produced in violent conditions, such as a supernova at the end of a massive star’s life.

Detailed differences in their abundances can tell us about cosmic ray sources and their trip through the galaxy. About 90% of the cosmic ray nuclei are hydrogen (protons), about 9% are helium (alpha particles), and all of the rest of the elements make up only 1%. Even in this one percent there are very rare elements and isotopes. Elements heavier than iron are significantly more rare in the cosmic-ray flux but measuring them yields critical information to understand the source material and acceleration of cosmic rays.

Even if we can’t trace cosmic rays directly to a source, they can still tell us about cosmic objects. Most galactic cosmic rays are probably accelerated in the blast waves of supernova remnants. The remnants of the explosions – expanding clouds of gas and magnetic field – can last for thousands of years, and this is where cosmic rays are accelerated. Bouncing back and forth in the magnetic field of the remnant randomly lets some of the particles gain energy, and become cosmic rays. Eventually they build up enough speed that the remnant can no longer contain them, and they escape into the galaxy.

Cosmic rays accelerated in supernova remnants can only reach a certain maximum energy, which depends on the size of the acceleration region and the magnetic field strength. However, cosmic rays have been observed at much higher energies than supernova remnants can generate, and where these ultra-high-energies come from is an open big question in astronomy. Perhaps they come from outside the galaxy, from active galactic nuclei, quasars or gamma ray bursts.

Or perhaps they’re the signature of some exotic new physics: superstrings, exotic dark matter, strongly-interacting neutrinos, or topological defects in the very structure of the universe. Questions like these tie cosmic-ray astrophysics to basic particle physics and the fundamental nature of the universe. (source)

The Pinwheel Galaxy - this giant disk of stars, dust and gas is 170,000 light-years across; nearly twice the diameter of the Milky Way. It is estimated to contain at least one trillion stars, approximately 100 billion of which could be like our Sun in terms of temperature and lifetime [6000x4690]

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Tilt-shift photo of the space shuttle Endeavour by NASA

https://www.nasa.gov/mission_pages/shuttle/flyout/multimedia/endeavour/11-05-16-2.html