I have recently been reading that space travel is strongly influenced by "space radiation" and how it poses a threat to human space exploration.

Does this radiation originate from stars like our Sun, or is it an omnipresent — let's just call it — "force" in space (such as cosmic noise) that doesn't have any specific source?

Also, can an amateur astronomer visualize this radiation in some way so as to be able to observe it?


2 Answers 2


Cosmic rays consist of both electromagnetic radiation (i.e. photons) of different frequencies (radio waves, IR, light, UV light, x-rays, gamma rays), as well as charged particles (protons, electrons, maybe even ions of light elements), and other stuff like neutrinos.

The vast majority of the radiation we encounter around earth will be from the sun, because it is so very close and basically a large radiating blob. Usually with isotropic (equally in all directions) radiating sources, the radiation intensity falls of with the square of the distance. That means radiation diminishes very, very fast. Go twice as far from the sun, and you only get a fourth of the radiation.

The EM radiation from UV and up (X-rays and gamma rays) is probably the most harmful. The earth's magnetic field shields us from these rays, but interplanetary travel will not have this benefit. X-rays and gamma rays may also come from supernovae and other stellar objects, which are far away, but will probably be much too faint to have an effect on astronauts. However, it can be picked up by sensitive specialized telescopes and satellites.

The charged particles may be a problem to spacecrafts and electronics onboard them, but can probably be dampened by shielding in the spacecraft, as to protect the astronauts.

Neutrinos are I think of no concern, since they hardly interact with other matter.

As an amateur, you will have problems detecting UV and above. Mainly because we are mostly shielded from this kind of radiation by the magnetosphere and the atmosphere.

You could detect particle radiation, by taking photos of northern lights, though... :)

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    $\begingroup$ Could you make a mention to Gamma Ray Bursts? If they happen near enough they can be dangerous too. $\endgroup$
    – Envite
    Dec 12, 2013 at 17:33
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    $\begingroup$ The magnetosphere has no effect on x rays or gamma rays as photons are not affected by magnetic fields. What protects us from them is the atmosphere which absorbs pretty much anything more energetic than UV. In general, external UV,x, and gamma rays are not really an issue, unless you were incredibly unlucky and a GRB happened while you were up there. Charged particles are the big concern for space exploration, the magnetosphere does protect us from them on earth and collects them in the van allen belt. $\endgroup$ Jun 29, 2014 at 4:10

All energized matter emits radiation. Radiation may consist of electromagnetic energy or particles, as covered in another answer. There are two types of radiation--ionizing and non-ionizing. Ionizing radiation is the type that we are predominantly concerned with danger of, because it can turn atoms that it passes through into ions--which is hazardous to human health. Non-ionizing radiation can still be dangerous if it generates enough heat to cause thermal ionization.

Ionizing radiation

  • Ultraviolet (of 10 to 125 nm wavelength) - electromagnetic radiation that is absorbed by the Earth's atmosphere but is present in space
  • X-ray - relatively harmless in the small doses that we get for medical work, but harmful in greater exposure
  • Gamma radiation - extremely small wavelength electromagnetic radiation emitted during nuclear processes
  • Alpha radiation - two protons and two neutrons bound as a single particle (helium-4 nucleus), cannot penetrate the skin at slow speeds, but high energy alpha particles can pose a danger to human health (cannot penetrate the atmosphere, but present in space)
  • Beta radiation - may be electrons (Beta-minus) or positrons (Beta-plus), do not typically penetrate the atmosphere but can readily penetrate unshielded human tissue
  • Neutron radiation - neutrons emitted by nuclear fission, highly dangerous, readily ionizes and can even make other materials radioactive

Non-ionizing radiation

  • Ultraviolet (lower part of the spectrum) - nonionizing but still high enough energy that it can have some dangerous effects on the human body
  • Visible light - the electromagnetic energy that we see, about 380-750 nm wavelength
  • Infrared - electromagnetic energy emitted by most objects at temperatures that we deal with on a daily basis, about 700 nm to 1 mm wavelength
  • Microwave - electromagnetic energy of wavelengths from 1 mm to 1 meter
  • Radio waves - electomagnetic energy of wavelengths greater than infrared

Used Wikipedia as a reference to organize and bolster information

In space we have numerous sources of radiation, since all energized matter emits radiation. Stars are a big factor emitting most types of radiation. Supernovae and black holes also emit radiation. Finally, some radiation has been propagating through the universe since the Big Bang. The Cosmic Microwave Background (CMB) radiation gives us a glimpse of the early universe.

There are many ways to observe radiation. Traditional telescopes make use of our natural ability to take in visible light and amplify it with lenses. Radio telescopes are also relatively easy for an amateur to get a hold of. Here's some instructions on how to build a simple radio telescope. Near-infrared light can be observed easily by an amateur with a regular telescope and infrared film, but this doesn't give us a lot more detail than visible light. Most infrared from space is absorbed by our atmosphere (more on infrared telescopes). UV and higher radiation would also be difficult to detect by an amateur since our atmosphere shields us from it, as well as particle radiation.

As one clever answerer posted, we can observe the stunning light effects that occur when particle radiation ionizes the upper atmosphere. Particle radiation is usually deflected by Earth's magnetic field, but sometimes travels along field lines toward the poles which is why the light effects of particle radiation are only observed in the arctic regions as the Northern and Southern lights.


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