Spectacular!

new photos of jupiter from the juno spacecraft | (good to know that van gogh had a say in how jupiter was designed)

Wide Field View of Great American Eclipse

A cosmic blossom

IC 5148 is a beautiful planetary nebula located some 3000 light-years away in the constellation of Grus (The Crane). The nebula has a diameter of a couple of light-years, and it is still growing at over 50 kilometres per second — one of the fastest expanding planetary nebulae known. The term “planetary nebula” arose in the 19th century, when the first observations of such objects — through the small telescopes available at the time — looked somewhat like giant planets. Although the name stuck, it represents the expanding shell of gas ejected from old red giant stars late in their lives.

And now this one resembles a lovely blossom with layered petals.

Credit: European Southern Observatory

For the first time, NASA’s Curiosity rover has captured a color image of a sunset on Mars.  (NASA via Smithsonian Magazine)

Any minute now, NASA’s Juno will be entering Jupiter’s orbit. So here is a photo of an aurora on Jupiter.

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)

Shot these with my phone through my telescope

Starburst galaxy NGC 4449 in the M94 galaxy group 13 million light-years away (Hubble image)

This photograph of Neptune was reconstructed from two images taken by Voyager 2’s narrow-angle camera, through the green and clear filters. At the north (top) is the Great Dark Spot, accompanied by bright, white clouds that undergo rapid changes in appearance.

Credit: NASA

The Wow! signal. 

A signal sequence that lasted for 72 seconds in 1977 but has never been seen again. The signal appeared to come from a globular cluster in the Sagittarius constellation, but to this day no definite answer for where the signal originated can be given.