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.

"Several times a year an atmospheric river [shown in the image on the right forming over Hawai'i]—a long, narrow conveyor belt of storms that stream in relentlessly from the Pacific Ocean—drops inches of rain or feet of snow on the U.S. west coast. Such a system triggered floods and mudslides in central and southern California this past weekend [2-3 February 2019]."

"Atmospheric rivers flow through the sky about a mile above the ocean surface, and may extend across a thousand miles of ocean to the coast. Some bring routine rain but the more intense systems can carry as much water as 15 Mississippi Rivers. The series of storms striking land can arrive for days or, occasionally, weeks on end. They hit west-facing coastlines worldwide, although the U.S. experiences more than most other national coasts."

The “atmospheric river scale” "ranks severity and impacts, from category 1 (weak) to category 5 (exceptional)." Read more...

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

## Cosmogony

This is an image of the painting about Urknall. Credit: Hans Breinlinger.

Cosmogony is any scientific theory concerning the coming into existence, or origin, of the cosmos or universe, or about how what sentient beings perceive as "reality" came to be.

Usually, the philosophy of cause and effect needs a beginning, a first cause. Modal logic may only require a probability rather than a sequence of events. The concept of uncountable suggests an unknown somewhere between a finite number of likely rationales and an infinite number of possibilities.

From a sense of time as moving forward from yesterday to today and onward to tomorrow, there is again a suggestion of a prehistoric time before the first hominins.

The use of any system of thought or emotion to perceive reality suggests that some existences may precede others.

When more detail becomes available an existence may be transformed into something, an entity, a source, an object, a rocky object, or out of existence.

As a topic in astronomy, cosmogony deals with the origin of each astronomical entity.

Observation, for example, using radiation astronomy may provide some details.

Theoretical astronomy may provide some understanding, or at least some perspective.

In astronomy, cosmogony refers to the study of the origin of particular astrophysical objects or systems, and is most commonly used in reference to the origin of the solar system.[1][2]

### References

1. Ian Ridpath (2012). A Dictionary of Astronomy. Oxford University Press.
2. M. M. Woolfson (1979). "Cosmogony Today". Quarterly Journal of the Royal Astronomical Society 20 (2): 97-114.
Selected topic

## Absorptions

A spectrum is taken of blue sky clearly showing solar Fraunhofer lines and atmospheric water absorption band. Credit: Remember the dot.

"[P]referential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon".[1]

"For quenched galaxies, the Hα absorption trough is deep and can be traced through the nucleus and along the major axis. It extends to a radius at or beyond 2 Rd [where Rd is the galaxy disk scale length] in all but three cases. This makes it possible to determine a velocity width from the optical spectrum as is done for emission line flux, with appropriate corrections between stellar and gas velocities (see discussion in Paper I, also Neistein, Maoz, Rix, & Tonry, 1999). In the few cases where a velocity width can also be measured from the H I data, it is found to be in good agreement with that taken from the Hα absorption line flux."[2]

### References

1. Craig F. Bohren. Atmospheric Optics (PDF).
2. Nicole P. Vogt and Martha P. Haynes, Riccardo Giovanelli, and Terry Herter (June 2004). "M/L, Hα Rotation Curves, and HI Gas Measurements for 329 Nearby Cluster and Field Spirals. III. Evolution in Fundamental Galaxy Parameters". The Astronomical Journal 127 (6): 3325-37. doi:10.1086/420703. Retrieved 2013-12-20.
Selected X-ray astronomy article
The combined image from the Chandra and XMM-Newton X-ray observatories of RCW 86 shows the expanding ring of debris that was created after a massive star in the Milky Way collapsed onto itself and exploded. Credit: Chandra: NASA/CXC/Univ. of Utrecht/J.Vink et al. XMM-Newton: ESA/Univ. of Utrecht/J.Vink et al.`{{fairuse}}`

SN 185 was a supernova which appeared in the year 185, near the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at Right ascension (RA) 14h 43m Declination (Dec) -62° 30', in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han.

On the right is a "combined image from the Chandra and XMM-Newton X-ray observatories of RCW 86 [in the constellation Circinus showing] the expanding ring of debris that was created after a massive star in the Milky Way collapsed onto itself and exploded. Both the Chandra and XMM images show low energy X-rays in red, medium energies in green and high energies in blue. The Chandra observations focused on the northeast (left-hand) side of RCW 86, and show that X-ray radiation is produced both by high-energy electrons accelerated in a magnetic field (blue) as well as heat from the blast itself (red)."[1]

"Properties of the shell in the Chandra image, along with the remnant's size and a basic understanding of how supernovas expand, were used to help determine the age of RCW 86. The new data revealed that RCW 86 was created by a star that exploded about 2,000 years ago. This age matches observations of a new bright star by Chinese astronomers in 185 A.D. (and possibly Romans as well) and may be the oldest known recordings of a supernova. Supernova explosions in galaxies like ours are rare, and none have been recorded in hundreds of years."[1]

Objects
Selected image

Comet Lulin was passing through the constellation Libra when the Swift Gamma-Ray Burst Mission imaged it on January 28, 2009. This image merges data acquired by Swift's Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). At the time of the observation, the comet was 99.5 million miles from Earth and 115.3 million miles from the Sun. Credit: .

Selected lesson

## First infrared source in Crux

This infrared image from NASA's Spitzer Space Telescope shows the nebula nicknamed "the Dragonfish". Credit: NASA/JPL-Caltech/Univ. of Toronto.

The first infrared source in Crux is unknown.

The field of infrared astronomy is the result of observations and theories about infrared, or infrared-ray sources detected in the sky above.

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

But, infrared rays from the Sun are intermingled with other colors so that the Sun may appear yellow-white rather than infrared.

The early use of sounding rockets and balloons to carry infrared, optical, or visual detectors high enough may have detected infrared-rays 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 infrared astronomy looking for the first astronomical infrared source discovered in the constellation of Crux.

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

Selected quiz

A new image from all three of NASA's Great Observatories--Chandra, Hubble, and Spitzer--has been created of the star-forming region 30 Doradus, also known as the Tarantula Nebula. Credit: NASA.

Electromagnetic astronomy is a lecture from the radiation astronomy department.

This is a quiz based on the lecture that you are free to take at any time or knowledge level.

Once you’ve read and studied the lecture itself, the links contained within the article and lecture, listed under See also and External links, you should have adequate background to take the quiz and score highly. The templates `{{radiation astronomy resources}}` and `{{principles of radiation astronomy}}` may also be helpful.

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.

Enjoy learning by doing!

 ...Archive Try the quiz...
Selected laboratory

## Electron beam heating laboratory

This is an X-ray image of the coronal clouds near the Sun. Credit: NASA Goddard Space Flight Center.

This laboratory is an activity for you to create a method of heating the solar corona or that of a star of your choice. While it is part of the astronomy course principles of radiation astronomy, it is also independent.

Some suggested entities to consider are electromagnetic radiation, electrons, positrons, neutrinos, gravity, time, Euclidean space, Non-Euclidean space, magnetic reconnection, or spacetime.

More importantly, there are your entities.

Usually, research follows someone else's ideas of how to do something. But, in this laboratory you can create these too.

Okay, this is an astronomy coronal heating laboratory.

Yes, this laboratory is structured.

I will provide an example of electron beam heating calculations. 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!

 ...Archive Experiment...
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.

 ...Archive Try the problems...
Selected X-ray astronomy pictures

This multiwavelength composite shows the supernova remnant IC 443, also known as the Jellyfish Nebula. Fermi GeV gamma-ray emission is shown in magenta, optical wavelengths as yellow, and infrared data from NASA's Wide-field Infrared Survey Explorer (WISE) mission is shown as blue (3.4 microns), cyan (4.6 microns), green (12 microns) and red (22 microns). Cyan loops indicate where the remnant is interacting with a dense cloud of interstellar gas.

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1. J. Vink; et al. (15 June 2004). RCW 86: New Evidence Links Stellar Remains to Oldest Recorded Supernova. 60 Garden Street, Cambridge, MA 02138 USA: Harvard-Smithsonian Center for Astrophysics. Retrieved 2016-02-12. Explicit use of et al. in: `|author=` (help)CS1 maint: location (link)