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.

The irregular galaxy NGC 1427A is passing through the Fornax cluster at nearly 600 kilometers per second (400 miles per second). Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA).

"The irregular galaxy NGC 1427A is a spectacular example of the resulting stellar rumble. Under the gravitational grasp of a large gang of galaxies, called the Fornax cluster, the small bluish galaxy is plunging headlong into the group at 600 kilometers per second or nearly 400 miles per second."

"Galaxy clusters, like the Fornax cluster, contain hundreds or even thousands of individual galaxies. Within the Fornax cluster, there is a considerable amount of gas lying between the galaxies. When the gas within NGC 1427A collides with the Fornax gas, it is compressed to the point that it starts to collapse under its own gravity. This leads to formation of the myriad of new stars seen across NGC 1427A, which give the galaxy an overall arrowhead shape that appears to point in the direction of the galaxy's high-velocity motion."

Selected lecture

Volcanic bombs are thrown into the sky and travel some distance before returning to the ground. This bomb is in the Craters of the Moon National Monument and Preserve, Idaho, USA. Credit: National Park Service.

In source astronomy, the question is "Where did it come from?"

Source astronomy has its origins in the actions of intelligent life on Earth when they noticed things or entities falling from above and became aware of the sky. Sometimes what they noticed is an acorn or walnut being dropped on them or thrown at them by a squirrel in a tree. Other events coupled with keen intellect allowed these life forms to deduce that some entities falling from the sky are coming down from locations higher than the tops of local trees.

Def. a source or apparent source detected or “created at or near the time of the [ event or] events”[1] is called a primary source.

Direct observation and tracking of the origination and trajectories of falling entities such as volcanic bombs presented early intelligent life with vital albeit sometimes dangerous opportunities to compose the science that led to source astronomy.

### References

1. primary source. San Francisco, California: Wikimedia Foundation, Inc. February 16, 2012. Retrieved 2012-07-14.
Selected theory

## Theoretical astronomy

This image is a theory for the interior of the Sun. Credit: Pbroks13.

Theoretical astronomy at its simplest is the definition of terms to be applied to astronomical entities, sources, and objects.

Def. an "expanse of space that seems to be [overhead] like a dome"[1] is called a sky.

Computer simulations are usually used to represent astronomical phenomena.

Part of the fun of theory is extending the known to what may be known to see if knowing is really occurring, or is it something else.

The laboratories of astronomy are limited to the observatories themselves. The phenomena observed are located in the heavens, far beyond the reach, let alone control, of the astronomical observer.[2] “So how can one be sure that what one sees out there is subject to the same rules and disciplines of science that govern the local laboratory experiments of physics and chemistry?”[2] “The most incomprehensible thing about the universe is that it is comprehensible.” - Albert Einstein.[2]

## References

1. Philip B. Gove, ed. (1963). Webster's Seventh New Collegiate Dictionary. Springfield, Massachusetts: G. & C. Merriam Company. p. 1221. Retrieved 2011-08-26.
2. Narlikar JV (1990). Pasachoff JM, Percy JR (ed.). Curriculum for the Training of Astronomers ‘’In: The Teaching of astronomy. Cambridge, England: Cambridge University Press.
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.
Selected X-ray astronomy article
Chandra X-ray Observatory and Inertial Upper Stage sit inside the payload bay on Space Shuttle Columbia mission STS-93.

X-ray astronomy satellites study X-ray emissions from celestial objects. Satellites, which can detect and transmit data about the X-ray emissions are deployed as part of branch of space science known as X-ray astronomy. Satellites are needed because X-radiation is absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and satellites.

Those in use today include the XMM-Newton observatory (low to mid energy X-rays 0.1-15 keV) and the INTEGRAL satellite (high energy X-rays 15-60 keV). Both were launched by the European Space Agency. NASA has launched the Rossi X-ray Timing Explorer (RXTE), the Swift, and Chandra observatories. One of the instruments on Swift is the Swift X-Ray Telescope (XRT).

Objects
Selected image

This ROSAT PSPC false-color image is of a portion of a nearby stellar wind superbubble (the Orion-Eridanus Bubble) stretching across the constellations Eridanus and Orion. Credit: David Burrows and Zhiyu Guo, Penn State Department of Astronomy & Astrophysics.

Selected lesson

## First ultraviolet source in Sagittarius

These two photographs were made by combining data from NASA's Galaxy Evolution Explorer spacecraft and the Cerro Tololo Inter-American Observatory in Chile. Credit: NASA/JPL-Caltech/JHU.

The first ultraviolet source in Sagittarius is unknown.

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

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

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

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

This is a lesson in map reading, coordinate matching, and searching. It is also a project in the history of ultraviolet astronomy looking for the first astronomical ultraviolet source discovered in the constellation of Sagittarius.

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 ultraviolet sources, you'll run into concepts and experimental tests that are an actual search.

Selected quiz

## Color astronomy quiz

Gases above Io's surface produced a ghostly glow that could be seen at visible wavelengths (red, green, and violet). Credit: NASA/JPL/University of Arizona.

Color astronomy is a lecture as part of the radiation astronomy department course development of principles of radiation astronomy.

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

To improve your scores, read and study the lecture, the links contained within, and listed under See also, External links and the `{{radiation astronomy resources}}` and `{{principles of radiation astronomy}}` templates. 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.

This quiz may need up to an hour to take and is equivalent to an hourly.

Suggestion: Have the lecture available in a separate window.

Enjoy learning by doing!

Selected laboratory

## Electric orbits

Electrons in a beam are moving in a circle in a magnetic field (cyclotron motion). Lighting is caused by excitation of atoms of gas in a bulb. Credit: Marcin Białek.

This laboratory is an activity for you to calculate an electric or magnetic orbit of an astronomical object. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

Some suggested entities to consider are electric fields, magnetic fields, mass, charge, Euclidean space, Non-Euclidean space, or spacetime.

Okay, this is an astronomy orbits laboratory, specifically to try out electric/magnetic orbits and where possible compare them to those calculated using gravity.

Yes, this laboratory is structured.

I will provide an example of an electric/magnetic orbit. 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

## Furlongs per fortnight

It's about the chains. Credit: Stilfehler.`{{free media}}`

Furlongs per fortnight is a problem set with a contained quiz that focuses on the fundamentals of observational and deductive astronomy. In the activity Energy phantoms you learned about the value of distance, or displacement, and motion, speed, velocity, and acceleration. Here, you can practice and test yourself on converting from units that may or have occurred in the literature to units popular today.

Notation: let the symbol ${\displaystyle R_{\oplus }}$ indicate the Earth's radius.

Notation: let the symbol ${\displaystyle R_{J}}$ indicate the radius of Jupiter.

Notation: let the symbol ${\displaystyle R_{\odot }}$ indicate the solar radius.

Both physics and astronomy use units and dimensions to describe observations.

Units of Physics and Astronomy
Dimension Astronomy Symbol Physics Symbol Conversion
time 1 day d 1 second s 1 d = 86,400 s[1]
time 1 "Julian year"[2] J 1 second s 1 J = 31,557,600 s
distance 1 astronomical unit AU 1 meter m 1 AU = 149,597,870.691 km[1]
angular distance 1 parsec pc 1 meter m 1 pc ~ 30.857 x 1012 km[1]

### References

1. P. K. Seidelmann (1976). Measuring the Universe The IAU and astronomical units. International Astronomical Union. Retrieved 2011-11-27.
2. International Astronomical Union "SI units" accessed February 18, 2010. (See Table 5 and section 5.15.) Reprinted from George A. Wilkins & IAU Commission 5, "The IAU Style Manual (1989)" (PDF file) in IAU Transactions Vol. XXB
Selected X-ray astronomy pictures

Chandra X-ray Observatory image of Cygnus X-1. Credit: Chandra: NASA/CXC.

Fields
Related portals
Wikimedia
 Wikiversity's sister projects Wikiversity is hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other multilingual and free-content projects: WikipediaFree-content encyclopedia WikibooksFree textbooks and manuals CommonsShared media repository IncubatorWikimedia incubator WiktionaryDictionary and thesaurus WikiquoteCollection of quotations WikinewsFree-content news BetawikiversityBetawikiversity project WikispeciesDirectory of species WikisourceFree-content library WikivoyageOpen travel guide PhabricatorMediaWiki bug tracker Meta-WikiWikimedia project coordination MediaWikiFree software development WikidataFree knowledge base Wikimedia LabsMediaWiki development Wikiversity is also available in other languages:Deutsch • Français • Русский • Čeština • मुखपृष्ठ • Italiano • Português • Español • العربية • Svenska • Suomi • Slovenščina • Ελληνικά • 日本語 • 한국어 • Other

Content by Subject
Arts · Humanities · Mathematics · Medicine · Science · Social Sciences · Technology