UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

What Are Cosmic Rays? — Showers of high energy particles occur when energetic cosmic rays strike the top of the Earth's atmosphere. Most cosmic rays are atomic nuclei: most are hydrogen nuclei, some are helium nuclei, and the rest heavier elements. Although many of the low energy cosmic rays come from our Sun, the origins of the highest energy cosmic rays remains unknown and a topic of much research. This drawing illustrates air showers from very high energy cosmic rays.
Credit: Simon Swordy (U. Chicago), NASA

Cosmic rays are atom fragments that rain down on the Earth from outside of the solar system. They blaze at the speed of light and have been blamed for electronics problems in satellites and other machinery.

First discovered in 1912, many things about cosmic rays remain a mystery more than a century later. One prime example is exactly where they are coming from. Most scientists suspect their origins are related to supernovas (star explosions), but the challenge is that cosmic ray origins appear uniform when you look across the entire sky.

History

While cosmic rays were only discovered in the 1900s, scientists knew something mysterious was going on as early as the 1780s. That's when French physicist Charles-Augustin de Coulomb — best known for having a unit of electrical charge named after him — observed an electrically charged sphere suddenly and mysteriously not being charged any more.

At the time, air was thought to be an insulator and not an electric conductor. With more work, however, scientists discovered that air can conduct electricity if its molecules are charged or ionized. This would most commonly happen when the molecules interact with charged particles or X-rays.

But where these charged particles came from was a mystery; even attempts to block the charge with large amounts of lead were coming up empty. On Aug. 7, 1912, physicist Victor Hess flew a high-altitude balloon to 17,400 feet (5,300 meters). He discovered three times more ionizing radiation there than on the ground, which meant the radiation had to be coming from outer space.

But tracing cosmic ray "origin stories" took more than a century. In 2013, NASA's Fermi Gamma-ray Space Telescope released results from observing two supernova remnants in the Milky Way: IC 433 and W44.

Among the products of these star explosions are gamma-ray photons, which (unlike cosmic rays) are not affected by magnetic fields. The gamma rays studied had the same energy signature as subatomic particles called neutral pions. Pions are produced when protons get stuck in a magnetic field inside the shockwave of the supernova and crash into each other.

In other words, the matching energy signatures showed that protons could move at fast enough speeds within supernovas to create cosmic rays.

Current science

We know today that galactic cosmic rays are atom fragments such as protons (positively charged particles), electrons (negatively charged particles) and atomic nuclei. While we know now they can be created in supernovas, there may be other sources available for cosmic ray creation. It also isn't clear exactly how supernovas are able to make these cosmic rays so fast.

Cosmic rays constantly rain down on Earth, and while the high-energy "primary" rays collide with atoms in the Earth's upper atmosphere and rarely make it through to the ground, "secondary" particles are ejected from this collision and do reach us on the ground.

But by the time these cosmic rays get to Earth, it's impossible to trace where they came from. That's because their path has been changed as they travelled through multiple magnetic fields (the galaxy's, the solar system's and Earth's itself.)

According to NASA, cosmic rays therefore come equally from all directions of the sky. So scientists are trying to trace back cosmic ray origins by looking at what the cosmic rays are made of. Scientists can figure this out by looking at the spectroscopic "signature" each nucleus gives off in radiation, and also by weighing the different isotopes (types) of elements that hit cosmic ray detectors.

The result, NASA adds, shows very common elements in the universe. Roughly 90 percent of cosmic ray nuclei are hydrogen (protons) and 9 percent are helium (alpha particles). Hydrogen and helium are the most abundant elements in the universe and the origin point for stars, galaxies and other large structures. The remaining 1 percent are all elements, and it's from that 1 percent that scientists can best search for rare elements to make comparisons between different types of cosmic rays.

Scientists can also date the cosmic rays by looking at radioactive nuclei that decrease over time. Measuring the "half life" of each nuclei gives an estimate of how long the cosmic ray has been out there in space.

Space radiation concerns

Earth's magnetic field and atmosphere shields the planet from 99.9 percent of the radiation from space. However, for people outside the protection of Earth's magnetic field, space radiation becomes a serious hazard. An instrument aboard the Curiosity Mars rover during its 253-day cruise to Mars revealed that the radiation dose received by an astronaut on even the shortest Earth-Mars round trip would be about 0.66 sievert. This amount is like receiving a whole-body CT scan every five or six days.

A dose of 1 sievert is associated with a 5.5 percent increase in the risk of fatal cancers. The normal daily radiation dose received by the average person living on Earth is 10 microsieverts (0.00001 sievert).

The moon has no atmosphere and a very weak magnetic field. Astronauts living there would have to provide their own protection, for example by burying their habitat underground.

The planet Mars has no global magnetic field. Particles from the sun have stripped away most of Mars’ atmosphere, resulting in very poor protection against radiation at the surface. The highest air pressure on Mars is equal to that at an altitude of 22 miles (35 kilometers) above the Earth’s surface. At low altitudes, Mars’ atmosphere provides slightly better protection from space radiation.

Surprise! The Universe Is Expanding Faster Than Scientists Thought — **Hubble Space Telescope view of the galaxy UGC 9391, which contains Cepheid variable stars and supernovas that scientists studied to calculate a newly precise value for Hubble's constant.**
**Credit: NASA, ESA, and L. Frattare (STScI)**

The universe is expanding 5 to 9 percent faster than astronomers had thought, a new study suggests.

"This surprising finding may be an important clue to understanding those mysterious parts of the universe that make up 95 percent of everything and don't emit light, such as dark energy, dark matter and dark radiation," study leader Adam Riess, an astrophysicist at the Space Telescope Science Institute and Johns Hopkins University in Baltimore, said in a statement.

Riess — who shared the 2011 Nobel Prize in physics for the discovery that the universe's expansion is accelerating — and his colleagues used NASA's Hubble Space Telescope to study 2,400 Cepheid stars and 300 Type Ia supernovas. [Supernova Photos: Great Images of Star Explosions]

This Hubble Space Telescope image shows Cepheid variable stars (circled in red) and a Type Ia supernova (blue "X") in the galaxy UGC 9391. Astronomers studied these and other "cosmic yardsticks" to calculate how fast the universe is expanding.
**Credit: NASA, ESA, and A. Riess (STScI/JHU)**

These are two different types of "cosmic yardsticks" that allow scientists to measure distances across the universe. Cepheids pulse at rates that are related to their true brightness, and Type Ia supernovas — powerful explosions that mark the deaths of massive stars — blaze up with consistent luminosity.

This work allowed the team to determine the distances to the 300 supernovas, which lie in a number of different galaxies. Then, the researchers compared these figures to the expansion of space, which was calculated by measuring how light from faraway galaxies stretches as it moves away from Earth, to determine how fast the universe is expanding — a value known as the Hubble constant, after famed American astronomer Edwin Hubble.

The new, unprecedentedly precise value for the Hubble constant comes out to 45.5 miles (73.2 kilometers) per second per megaparsec. (One megaparsec is equivalent to 3.26 million light-years.) Therefore, the distance between cosmic objects should double 9.8 billion years from now, the researchers said.

The new figure is 5 to 9 percent higher than previous estimates of the Hubble constant, which relied on measurements of the cosmic microwave background radiation — the light left over from the Big Bang that created the universe 13.8 billion years ago.

There are a number of possible explanations for this discrepancy, study team members said.

**Illustration showing the three steps astronomers used to measure the universe's expansion rate to an unprecedented accuracy, reducing the total uncertainty to 2.4 percent.**
**Credit: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU)**

For example, the mysterious force known as dark energy, which is thought to be behind the universe's accelerating expansion, may be stronger than astronomers had thought. It's also possible that "dark radiation" — an unknown, superspeedy subatomic particle or particles that existed shortly after the Big Bang — could be playing a role that hasn't been taken into account, the researchers said.

Enigmatic dark matter, which is thought to be four times more abundant than "normal" matter throughout the universe, could also have some weird and unappreciated characteristics. Or maybe there's something important missing from Einstein's theory of gravity, the researchers said.

In short, there's a lot of work left to do before astronomers can fully appreciate the meaning of the new results.

"We know so little about the dark parts of the universe; it's important to measure how they push and pull on space over cosmic history," study co-author Lucas Macri, of Texas A&M University, said in the same statement.

The new study has been accepted for publication in The Astrophysical Journal.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.