This image is a composite of several types of radiation astronomy: radio, infrared, visual, ultraviolet, soft and hard X-ray. Credit: NASA.

Radiation astronomy is astronomy applied to the various extraterrestrial sources of radiation, especially at night. It is also conducted above the Earth's atmosphere and at locations away from the Earth, by satellites and space probes, as a part of explorational (or exploratory) radiation astronomy.

Seeing the Sun and feeling the warmth of its rays is probably a student's first encounter with an astronomical radiation source. This will happen from a very early age, but a first understanding of the concepts of radiation may occur at a secondary educational level.

Radiation is all around us on top of the Earth's crust, regolith, and soil, where we live. The study of radiation, including radiation astronomy, usually intensifies at the university undergraduate level.

And, generally, radiation becomes hazardous, when a student embarks on graduate study.

Cautionary speculation may be introduced unexpectedly to stimulate the imagination and open a small crack in a few doors that may appear closed at present. As such, this learning resource incorporates some state-of-the-art results from the scholarly literature.

The laboratories of radiation astronomy are limited to the radiation observatories themselves and the computers and other instruments (sometimes off site) used to analyze the results.

Selected resource
The universe within 1 billion light-years (307 Mpc) of Earth is shown to contain the local superclusters, galaxy filaments and voids. Credit: Richard Powell.

"Galaxies and clusters of galaxies are not uniformly distributed in the Universe, instead they collect into vast clusters and sheets and walls of galaxies interspersed with large voids in which very few galaxies seem to exist. The map above shows many of these superclusters including the Virgo supercluster - the minor supercluster of which our galaxy is just a minor member. The entire map is approximately 7 percent of the diameter of the entire visible Universe."

More resources...
Selected lecture

## Strong forces

"In field theory it is known that coupling constants “run”. This means that the values of the coupling constants that one measures depend on the energy at which the measurement is performed. [...] the three different coupling constants [one each for the strong force, electromagnetic force, and the weak force] of the standard model seem to converge to the same value at an energy scale of about 1016 GeV [...] This suggests that there is only one coupling constant at high energies and most likely only one symmetry group. [...] The current belief [is] that the electromagnetic, weak and strong forces [are] unified at about 1016 GeV [as such] one has to rely on [the] particle physics interactions which can lead to electromagnetic radiation and cosmic rays".[1]

### References

1. Tanmay Vachaspati (1998). "Topological defects in the cosmos and lab". Contemporary Physics 39 (4): 225-37. doi:10.1080/001075198181928. Retrieved 2013-11-05.
Selected theory

## Stellar fissions

W Ursae Majoris is an eclipsing binary, specifically a contact binary with a common envelope. The primary component has a radius of 1.08 solar. The secondary has a 0.78 solar radius. Credit: Aladin at SIMBAD.
This image shows the star Merope (23 Tauri) in the Pleiades. Credit: Henryk Kowalewski.

Star fission is the splitting of a star at a critical angular momentum, or period in its history, with the consequence of zero-age contact in the resultant binary star. This splitting may have its highest probability of occurring during early star formation.

Def. any small luminous dot appearing in the cloudless portion of the night sky, especially with a fixed location relative to other such dots or a luminous celestial body, made up of plasma (particularly hydrogen and helium) and having a spherical shape is called a star.

When any effort to acquire a system of laws or knowledge focusing on a stellar astr, aster, or astro, that is, any natural star in the sky especially at night, succeeds even in its smallest measurement, stellar astronomy is the name of the effort and the result.

Selected topic

## Emissions

The Hubble Space Telescope [Advanced Camera for Surveys] ACS image has H-alpha emission of the Red Rectangle shown in blue. Credit: ESA/Hubble and NASA.

"[T]he extended red emission (ERE) [is] observed in many dusty astronomical environments, in particular, the diffuse interstellar medium of the Galaxy. ... silicon nanoparticles provide the best match to the spectrum and the efficiency requirement of the ERE."[1]

### References

1. Adolf N. Witt, Karl D. Gordon and Douglas G. Furton (July 1, 1998). "Silicon Nanoparticles: Source of Extended Red Emission?". The Astrophysical Journal Letters 501 (1): L111-5. doi:10.1086/311453. Retrieved 2013-07-30.
Objects
Selected image

On the left is a Chandra X-ray Observatory X-ray image that reveals a large cloud of hot gas that extends throughout the Hydra A galaxy cluster. Image is 2.7 arcmin across. Right ascension (RA) 09h 18m 06s Declination (Dec) -12° 05' 45" in the constellation Hydra. Observation date: October 30, 1999. Instrument: ACIS. Credit:NASA/CXC/SAO. On the right is an image that has the radio image of Greg Taylor, NRAO, overlain on the X-ray image from Chandra. The radio source Hydra A originates in a galaxy near the center of the cluster. Optical observations show a few hundred galaxies in the cluster. Credit:NASA/CXC/SAO; Radio: NRAO.

Selected lesson

## First positron source in Phoenix

Positron astronomy results have been obtained using the INTEGRAL spectrometer SPI shown. Credit: Medialab, ESA.

The first positron source in Phoenix is unknown.

The field of positron astronomy is the result of observations and theories about positron sources detected in the sky above.

The first astronomical positron source discovered may have been the Sun.

But, positrons from the Sun are intermingled with other radiation so that the Sun may appear as other than a primary source for positrons.

The early use of sounding rockets and balloons to carry positron detectors high enough may have detected positrons from the Sun as early as the 1940s.

This is a lesson in map reading, coordinate matching, and researching. It is also a research project in the history of positron astronomy looking for the first astronomical positron source discovered in the constellation of Phoenix.

Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary level and perhaps even a primary education level.

Some of the material and information is at the college or university level, and as you progress in finding positron sources, you'll run into concepts and experimental tests that are actual research.

Selected quiz

## Cyan astronomy quiz

The visual image shows the natural cyan color of planetary nebula NGC 7048. Credit: Aladin from CDS.

Cyan astronomy is a lecture as part of the radiation astronomy department course on the principles of radiation astronomy.

You are free to take this quiz based on cyan astronomy at any time.

To improve your score, read and study the lecture, the links contained within, listed under See also, External links and in the `{{principles of radiation astronomy}}` template. This should give you adequate background to get 100 %.

As a "learning by doing" resource, this quiz helps you to assess your knowledge and understanding of the information, and it is a quiz you may take over and over as a learning resource to improve your knowledge, understanding, test-taking skills, and your score.

Suggestion: Have the lecture available in a separate window.

To master the information and use only your memory while taking the quiz, try rewriting the information from more familiar points of view, or be creative with association.

Enjoy learning by doing!

Selected laboratory

## Cratering astronomy laboratory

The crater in Santa Ana Volcano is photographed from a United States Air Force C-130 Hercules flying above El Salvador. Credit: José Fernández, U.S Air Force.

This laboratory is an activity for you to create or analyze a cratering. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

Some suggested types of cratering to consider include a lightning strike, a bullet shot into some material, a water droplet hitting the surface of a beaker of water, a subterranean explosion, a sand vortex, or a meteorite impact.

More importantly, there is your cratering idea. And, yes, you can crater a peanut butter and jelly sandwich if you wish to.

Okay, this is an astronomy cratering laboratory, but you may create what a crater is. Another example is a volcanic crater.

I will provide an example of a cratering experiment. The rest is up to you.

Please put any questions you may have, and your laboratory results, you'd like evaluated, on the laboratory's discussion page.

Enjoy learning by doing!

Selected problems

## Cosmic circuits

The arcing, graceful structure is actually a bow shock about half a light-year across, created from the wind from the star L.L. Orionis colliding with the Orion Nebula flow. Credit: NASA.
This diagram suggests a simple electrical circuit. Credit: GorillaWarfare.

Voyager 1 has found only electrons streaming into the heliosphere from elsewhere in the galaxy. This problem set poses several problems to calculate the possibility that a simple electrical circuit is involved.

The diagram at right suggests a simple electrical circuit.

Def. an enclosed path of an electric current is called a circuit.

In the diagram at right are three components:

1. a voltage (V), or current (i), source,
2. an enclosed path, and
3. a resistance, or resistor, (R).

According to Ohm's law:

${\displaystyle V=iR.}$

With respect to an enclosed path, consider a path from outside the heliosphere, inward toward the Sun, and out again. Let the incoming electrons have 500 MeV of energy and a flux of 8.5 x 104 e- cm-2 s-1.

Def. a time rate of flow of electric charge is called a current.

Def. that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 x 10–7 newton per metre of length is called an ampere.

Def. an amount of electrostatic potential between two points in space is called a voltage.

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