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Night Sky

August night sky

Charlie Christmann

They come from outer space

In the late 1800s, scientists were beginning to understand radioactivity. Many elements were known to be radioactive, throwing off bits and pieces of their nuclei and transmuting into lighter elements. The bits flying away were discovered to be protons, neutrons, alpha particles (two protons and two neutrons), and beta (electrons) particles. In the process, gamma rays were also produced. Gamma rays are high-energy photons that can penetrate massive objects and cause damage to living tissues.

It was believed that these radioactive particles and rays were the source of ionization (electrically charging) in the atmosphere. Since only radioactive elements were known on Earth, the source of the ionizing radiation must be the Earth.

As new science is performed, old ideas must be reconciled; and when experiments were made around 1900, it was found that more of these ionizing particles were at the top of the Eiffel Tower than at the surface or a few feet under water.

The definitive experiment was carried out in 1912 by Victor Hess. He conducted several experiments where he launched high accuracy electrometers in balloons to measure the ionization rates in our atmosphere. What he discovered was that the ionization rate was much greater the higher you ascend in the atmosphere. That discovery won him the Nobel Prize in Physics in 1936.

So, what was the source of all that radiation? Space. The Earth was being bombarded from outer space. About a decade later, Robert Millikan was able to prove that the electric field in the atmosphere observed by Hess was instead a flux of photons and electrons, that he later termed “cosmic rays.” Since that time, scientists and astronomers have been trying to find the source of these rays.

In reality, the “rays” are not actually photons, but bits and pieces of atomic nuclei hitting our atmosphere at extremely high speeds. When one of the particles hits an atom of air, it is just like what happens in our particle accelerators, such as the Large Hadron Collider near Geneva: a spray of new particles, x-rays, and gamma rays are produced and shower down toward Earth. In this fashion, Earth protects us at the surface from the harmful effects of cosmic rays. The Earth also protects us with her magnetic field, shunting most of the lower energy rays either around and away from us, or toward the polar regions.

Unfortunately, astronauts do not have the luxury of the Earth’s atmosphere to protect them. Cosmic rays can rip right through an astronaut, damaging DNA and possibly causing cancer and memory loss over the long-term. Apollo astronauts in route to the moon left the protection of both the atmosphere and our magnetic field. When their eyes became accustomed to the dark, they started to see flashes of light. It is thought that the cause was cosmic rays passing through the eyes and retinas registering as a flash or streak of light in the brain.

So, where do those cosmic rays originate? Lower energy cosmic rays were known to originate from our own sun as it throws off flares and coronal mass ejections (CMEs) in the form of mostly protons and electrons. Higher energy protons and heavier charged particles—larger nuclei than helium—arriving with energies hundreds to thousands of times more powerful than anything we have created in our particle accelerators were a mystery at the time.

By the 1990s it was believed that super nova explosions and black holes fired off most of these ultra-high energy particles—all of them from outside our own galaxy. If true, these charged particles have traveled between the galaxies and through a vast array of magnetic fields. Magnetic fields interact with charged particles and change their direction. Since we do not know very much about magnetic fields in our own galaxy, and even less in intergalactic space, we may never be able to track their origin.

If super novae or black holes feeding on gas are the source, copious amounts of neutrinos would also be produced, according to current models. Gama Ray Bursts (GRB) are thought to be the result of a super nova explosion that can be seen half way across the known universe.

A recent experiment using an orbiting gamma ray telescope to detect GRBs, and a giant block of ice at the South Pole, called IceCube, to detect neutrinos, seemed to show that GRBs are not producing the expected neutrinos. That result tends to eliminated GRBs and super novae as a source, leaving the giant black holes at the centers of active galaxies as the last plausible source, for now. But, after more than one hundred years of studying the most energetic rays, we still really do not know how they get accelerated to such high velocities or what is firing them off.

Perseid meteor shower

The Perseid meteor shower peaks on August 12, but start watching on the 10th from midnight to dawn.

The planets and moon

  • Mercury is low on the ENE horizon before sunrise mid-month.
  • Bright Venus is high in the east before sunrise.
  • Mars is low in the WSW after sunset. Look just above the horizon an hour after sunset.
  • Jupiter is also a morning “star.” Look above Venus in the east before sunrise.
  • Saturn joins Mars low in the WSW after sunset. Mars and Saturn are at their closest on the 2nd. Saturn will be above Spica with • Mars to the right of the star. Arcturus floats above the trio.
  • There are two full moons this month: the 1st and the 31st. The new moon is on the 17th.

Rio Rancho Astronomical Society hosts monthy meeting and stargaze

On August 25, at 8:00 pm., the Rio Rancho Astronomical Society will host its monthly meeting and stargaze at Coronado State Monument. The stargaze will follow the meeting, weather permitting. Telescopes provided by members of the Rio Rancho Astronomical Society will show views of Mars and Saturn, as well as various nebula, star clusters, and galaxies. The public is invited to attend both events.

For details, go to www.rrastro.org or call 220-5492.

 
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