Q&A Cosmic Ray Science

The name cosmic ray has actually caused much confusion, because it is an improper description of the phenomenon. Cosmic rays are very energetic charged particles that rain down on us from space and constantly bombard the earth. They are not "rays", such as light.
More details.

When cosmic ray particles enter our atmosphere, they interact with molecules to produce a shower of secondary lower- energy particles. It is the detection of these secondary particles that allow us to study cosmic rays.
More details.

That depends on the energy of the cosmic ray. At the lower energy levels, around 10⁹ eV, possibly many thousands of secondary cosmic ray shower particles go through your body each second. As the energy level increases, the number of particles becomes more and more rare. At 10¹⁹eV, only about two particles per square mile arrives at the upper atmosphere per year. Above 10²⁰eV, only about two particles per square mile arrive each century. Therefore, to find and measure these rare events, a high-energy cosmic ray study needs a truly giant detector, like the 35-mile by 35-mile detector in Argentina and the even larger 80-mile by 100-mile array of tanks proposed for southeastern Colorado.

The Auger project uses two means to detect cosmic ray showers -- fluorescence telescopes and specially designed tanks filled with water and electronic light detectors.
More details.

Something out there -- no one knows what -- is hurling these incredibly energetic particles around the universe. This has been an unaswered question for over 40 years! Only recently, has Auger South data given us clues to possibly link these particles to a special sort of galaxy with a very active center - probably containing a huge black hole. However, this mystery is far from being solved. Scientists love such mysteries, because solving one represents the opportunity to learn something about the universe. Basic scientific research, such as this project, has and will continue to provide the necessary information to make enormous positive changes in our lives and society.
More details.

It is a pure science project - very much like a regular observatory, which might use a telescope to look at starlight. However, the Auger Project does not observe starlight. Instead it measures a different kind of natural particle that arrives at the earth from outer space. The particles measured are mostly likely the hard central core, or nucleus, of atoms. When one of these particles arrives at the atmosphere, it makes a large shower of secondary particles, and it is some of these millions of shower particles that are measured by the tanks.

The Pierre Auger Project is an international collaboration involving about 370 physicists and engineers from 17 countries in North and South America, Europe and Asia. It is named after the physicist who, in the 1930s, discovered the above mentioned shower of particles. In general, these particles are called "cosmic rays."

No. The cosmic rays will travel to earth no matter whether the project is built or not -- scientists will only observe what happens naturally.

No. Cosmic rays are a natural occurrence, and are not harmful at the Earth's surface.
More details.

No - not yet, but maybe someday. At this point, we don't understand enough about the ultra-high energy cosmic rays and how we might effectively collect their energy.

No, it is highly unlikely because of their huge range of energies, the high frequency of some of them and their randomness. We would expect energy signals from another civilization to be regular in time, of a fairly consistent energy and be quite rare (unless their are inhabited planets all over the cosmos that have reached our level of progress or higher).

No. Fortunately for us, cosmic rays usually react with the most common molecule in our atmosphere - nitrogen. Ozone is a special form of oxygen and it is not very common in our atmosphere (even though it plays a large role in protecting us from ultra-violet radiation).

We do not know of any current life form that depends on cosmic rays, however, cosmic rays may have played a large role in the life process on earth. There are theories that the energies in cosmic rays may have helped to create or change life in the past, when the Earth's atmosphere may have been very different than it is today. If the atmosphere was much thinner in the past, a larger amount of the energy from cosmic rays would have reached the surface of the Earth. Some scientists have hypothesized that this could have had an effect on the development of life or could have changed whatever life forms were present at the time.

After studying cosmic rays for the last century, scientists think that many of the lower and some of the medium energy cosmic rays come from stars. We certainly do receive cosmic rays on Earth that originate from our sun. However, these rays origins are difficult to study as they get deflected by the many magnetic field associated with other stars and planets.

Cosmic rays are some of the emmisions that come from our sun. During high solar activity, there probably are more cosmic rays being produced. However, all other emissions from the sun are also increased at this time and it is difficult to say if electromagnetic disturbances on the Earth are caused by "more" cosmic rays or some other solar emmission.

There have already been many instruments aboard spacecraft and satellites that have studied cosmic rays. However, until recently, there have not been proposals for a project strictly dedicated to studying cosmic rays to be based in space.
More details.

High energy and ultra-high energy cosmic rays have an enormous amount of energy for the size carrier. It is very difficult for us to imagine and hypothesize what process could create so much energy in so small of package. This is one reason for scientists interest in these cosmic rays. The other has to do with their ability to remain relatively undeflected. The ultra-high energy cosmic rays may have enough energy to plow through the magnetic fields it encounters and come to use in an "almost stright line" path. The detection of these cosmic rays would allow us to look back in the arrival direction and hopefully find the object that produced the cosmic ray. This is the second reason for scientists interest. Finally, we would like to know if there is an upper limit on the amount of energy a cosmic ray can have. All of these unanswered questions but tantillizing possibilities make high energy cosmic ray study very exciting.

Yes, with sophisticated instruments. Because cosmic ray particles are so small, and they interect with material to produce very faint ultra-violet light, our eyes can't detect cosmic rays. We need sophisticated and sensitive instruments to let us know when they are around.

By the time the original cosmic ray reaches the Earth's surface, it has probably lost most of its energy. This energy has gone into collisions with particles in our atmosphere and into creating secondary shower particles. In order to recover much of this energy, we would have to intercept most of the secondary particles - which is not practical because of the large area they are spread over and the different altitudes they are created at. Due to their extremely small size and random nature, cosmic rays and secondary shower particles will probably never be a pratical source of energy.

Yes. Since the discovery of "penetrating atmospheric radiation" in 1912 by Victor Hess (later named cosmic rays by Robert Millikan), scientists have been developing more sophisticated ways to measure these particles. Many different balloon based and finally ground based instruments started to measure comic rays during the 1930's. There was an experiment done in Russia during the late 1940's. There were some more famous studies done in Utah and England during the 1960's. More expansive and larger observatories were built in the 1980's and 1990's. There are a number of experiments running today and being proposed for tomorrow to continue to study cosmic rays. Many of the Auger scientists have been working with cosmic rays for most of their lives asd they have continued to provide answers and more mysteries about the cosmos.

Because the Earth is a sphere, standing in one place on the Earth does not allow you to see the entire heavens. One reason is because of the shape of the Earth, but another reason is that is is not possible to see objects in space well near the horizon (due to the Earth's atmosphere and pollution in it). Therefore, we need an observatory at a middle latitude south of the equator to see the southern sky well and an observatory at a middle latitude north of the equator to see the northern sky well. In order to make sure we don't miss any possible cosmic rays arriving anywhere at the earth, we need to be able to loook in the north and the south - hence 2 detector arrays make up the one Auger cosmic ray observatory.

Do astronauts study cosmic rays?

Yes. Ever since NASA started to send people into space they have been studying cosmic rays. Please visit their web page to learn more about what they have done and learned.

People have recently begun to ask this question - but there doesn't appear to be any danger because people don't live at high enough altitudes. There have recently been some studies to try to determine if pilots or airline stewards/stewardesses are in the air long enough and at high enough altitudes to receive any significant amount of exposure to cosmic rays, but the answers are not yet clear.

As far as we know, the only time a human can be affected by a cosmic ray is in outer space as an astronaut. Space agencies around the world have worked very hard since spaceflight began to protect astronauts from the energy contained in some cosmic rays. They have had some success, but it is still a major problem. In fact, it is the largest problem keeping humans from prolonged space journeys - such as to Mars. Until a suitable shield can be designed and manufactured, cosmic ray exposure in outer space limits our space travel possibilities.

When they were first discovered in 1912 by Victor Hess, no one knew what type of object it was. Since our only knowledge at that time was of light and other forms of radiation coming from space, the term "cosmic ray" was proposed and accepted by the scientific community. We assumed it had to be another form of radiation because we knew of no other type of information coming from space. We have since learned that many types of particle also reach us from outer space besides electromagnetic radiation. However, the name has stuck and we still call these particles "cosmic rays".

Probably, but not the medium, high or ultra-high energy cosmic rays (these are too rare to cause any disruptions). Solar storms are most likely a huge spray of very low energy cosmic rays that originate at the sun. These are responsible for the Northern lights and probably do create some communication interference.

Most of the cosmic rays that reach us come from our sun. They are solar particles that are most likely accelerated by the solar wind (which is itself a stream of particles being thrown off by the energy of the sun). The medium energy cosmic rays are thought to be accelerated by supernovas (the explosions of some stars associated with the end of their lives) or possibly multiple interactions with the magnetic field of our galaxy. The higher and ultra-high energy cosmic rays have been a mystery for many decades. It was only last year that the Pierre Auger Observatory published results that possibly link these particles to very massive/active black holes outside of our own galaxy in the center of certain other types of galaxies. Scientists are continually learning more about cosmic rays of all energies.

The Auger Project web site has more information, and in particular more questions and answers about cosmic rays and the science of the Auger Project.