Common Unit Prefixes and Radiation Types Used in Astronomy

Astronomy:

Common Unit Prefixes and Radiation Types Used in Astronomy

Published:
Updated: April 24, 2009, 12:06 am
Topics: Astronomy
Content Source: The RXTE Learning Center - NASA

Unit Prefixes Commonly Used in Astronomy

Standard prefixes for the SI (International Standard) units of measure
Multiples
(Large)		 Name   deca- hecto- kilo- mega- giga- tera- peta- exa- zetta- yotta-
Symbol   da h k M G T P E Z Y
Factor 100 101 102 103 106 109 1012 1015 1018 1021 1024
 
Subdivisions
(Small)		 Name   deci- centi- milli- micro- nano- pico- femto- atto- zepto- yocto-
Symbol   d c m µ n p f a z y
Factor 100 10−1 10−2 10−3 10−6 10−9 10−12 10−15 10−18 10−21 10-24

Standard prefixes for the SI units of measure.
Source: Wikipedia. Table links lead to content in Wikipedia.

 

Radiation Types Commonly Used in Astronomy

Frequency Range (Hz) Wavelength Range Energy Range Type of Radiation
1020-1024 10-12 - 10-16 m .4-4000 MeV gamma-rays
1017 - 1020 1 nm - 1 pm .4-400 keV X-rays
1015 - 1017 400 - 1 nm 4-400 eV ultraviolet light
4.3 - 7.5 x 1014 700-400 nm 1.77-3.1 eV visible light
1012 - 1014 2.5 mm - 700 nm 4-400 meV infrared light
108 - 1012 1 mm - 2.5 mm 40-4000 meV microwaves
100 - 108 108 - 1 m 400-400,000 peV radio waves

 

Examples of What Different Wavelengths "Look Like"

Radio Waves
Milky Way Galaxy - Radio Image The radio image of our Galaxy, taken at a frequency of 408 MHz, is a mosaic of data taken by the Jodrell Bank, Effelsberg and Parkes radio telescopes. Near this frequency, cosmic radio waves are generated by high energy electrons spiraling along magnetic fields. This false color image shows the Galactic plane running horizontally through the center, however, you will find that no stars are visible. Instead, many of the bright sources near the plane are distant pulsars, star forming regions, and supernova remnants, while the grand looping structures are pieces of bubbles blown by local stellar activity. External galaxies like Centaurus A, located above the plane to the right of center, and the Large Magellanic Cloud (LMC) (below and right) also shine in the radio sky.
 

Infrared Light
Infrared Image of the Milkyway Galaxy. Infrared Image of the Milkyway Galaxy. The infrared image taken by the Infrared Astronomical Satellite (IRAS), shows the center region of our Galaxy. The hazy, horizontal S-shaped feature that crosses the image is faint heat emitted by dust in the plane of the solar system.

 

Visible Light
Optical/Visible Light Image of the Milkyway Galaxy. Optical/Visible Light Image of the Milkyway Galaxy. The optical picture is one we may be most familiar with. It shows something similar to what you would see if you drove out into the country in the summer and looked towards the center of our Galaxy. Large optical telescopes can show us fine detail that our eyes are unable to resolve.

 

X-rays
X-ray Image of the Milkyway Galaxy. X-ray Image of the Milkyway Galaxy. The X-ray image is from the ROSAT All-Sky Survey. It shows X-rays at energies of .75 keV. This image is dominated by the radiation from the north polar spur and from the large-scale central region of our Galaxy, which contains hot interstellar matter and tens of thousands of unresolved point sources. Near the equator in the left half of the image, the Cygnus superbubble becomes visible as a broken yellow and red ring. The Vela supernova remnant is an isolated red spot towards the right side of the image.
 

Gamma-rays
Gamma-ray Image of the Milkyway Galaxy. Gamma-ray Image of the Milkyway Galaxy. The Gamma-ray image includes all photons with energies greater than 100 MeV. At these extreme energies, most of the celestial gamma-rays originate in collisions of cosmic rays with hydrogen nuclei in interstellar clouds.

 

References

  • The Multi-wavelength Milkyway – The RXTE Learning Center, a service of the Astrophysics Science Division at NASA/GSFC.
  • Units – The RXTE Learning Center, a service of the Astrophysics Science Division at NASA/GSFC.

Related EoC Articles

External Links


Disclaimer: This article is taken wholly from, or contains information that was originally published by, The RXTE Learning Center - NASA. Topic editors and authors for the Encyclopedia of the Cosmos may have edited its content or added new information. The use of information from The RXTE Learning Center - NASA should not be construed as support for, or endorsement by, that organization for any new information added by EoC personnel, or for any editing of the original content.
Original content retrieved from "http://heasarc.nasa.gov/docs/xte/learning_center/universe/milkyway.html."

Citation

NASA. (Contributing Author); Bernard Haisch (Topic Editor). 2009. "Article Name." In: Encyclopedia of the Cosmos. Eds. Bernard Haisch and Joakim F. Lindblom (Redwood City, CA: Digital Universe Foundation). [First published November 23, 2008].
<http://www.cosmosportal.org/articles/view/135722/>

 

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