Frequently Asked Questions About ...
Astronomy
We receive questions from around the world on a wide variety of Astronomy and related subjects. The following is a list of frequently asked questions and answers from various NOAO staff and astronomers. We also provide an extensive list of Astronomy and Related Links for more information. See also the Frequently Asked Questions About Being an Astronomer.
- How do I name a star after my Mother/Father/Girlfriend/Boyfriend/etc?
- When is the next Blue Moon?
- I saw a bright light in the sky last night. Do you know what it was?
- How do you determine focal length of a telescope's mirror?
- How do sun spots affect tree growth?
- How does the Earth's magnetic field shield us from harmful effects of the sun?
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Astronomy Magazine
http://www.kalmbach.com/astro/
POETRY
http://image.gsfc.nasa.gov/poetry/
Harvard-Smithsonian
Center for Astrophysics
http://sao-www.harvard.edu/
Midlands Technical College Astronomy Club
http://www.mid.tec.sc.us/mtcac/clubpages/00_welcome.htm
Peoria Astronomical Society
http://astronomical.org/pasmenu.htm
Astronomy 162
Stars, Galaxies, and
Cosmology
http://csep10.phys.utk.edu/astr162/lect/index.html
Sky and Telescope - Sky at a Glance
http://www.skypub.com/sights/sights.shtml
The Tucson Amateur Astronomy Association
http://www.tucsonastronomy.org/
Stars and Constellations
http://www.astro.uiuc.edu/~kaler/sow/sow.html
Flandrau Science Center
http://www.flandrau.org/
International Dark-Sky Association (IDA)
http://www.darksky.org/
Telescope Links
UCSB Remote Access Astronomy Home Page
http://www.deepspace.ucsb.edu/rot.htm
The Hubble Space Telescope
http://www.stsci.edu/proof/hubble.html
Remote and Robotic Telescopes
http://www.telescope.org/rti/automated.html
Astromart Global Index
http://www.astromart.com/
Hubble Heritage
http://heritage.stsci.edu/index.html
Capella Plans
http://solar.physics.montana.edu/larson/Capella/index.html
Amateur Telescope Making Journal
http://www.atmjournal.com/
Lunar Links
U.S. Naval Observatory Astronomical Applications Department Data Services
http://aa.usno.navy.mil/AA/data/
Great Lunar Links
http://www.evansville.net/~slk/links.html
Virtual Reality Moon Phase Pictures
http://tycho.usno.navy.mil/vphase.html
Earth and Moon Viewer
http://www.fourmilab.ch/earthview/vplanet.html
Planet Links
Stars and Constellations
http://www.astro.uiuc.edu/~kaler/sow/sow.html
Planet Quest
http://library.thinkquest.org/27322/frameset.php
The Minor Planet Mailing List
http://www.bitnik.com/QHO/MPList.html
SEDS Galaxy: Planets and the Solar System
http://www.seds.org/galaxy/planets.html
"Europa Wedges" Educational Activity Page
http://www.jpl.nasa.gov/galileo/wedges/
Solar System Live
http://www.fourmilab.ch/solar/
IAU: Minor Planet Center
http://cfa-www.harvard.edu/iau/mpc.html
Solar System Exploration Home Page
http://sse.jpl.nasa.gov/
The Nine Planets
http://www.seds.org/nineplanets/nineplanets/nineplanets.html
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The International Astronomical Union is the only recognized star-naming organization, and it does not sell names.
There are certain commercial and some nonprofit organizations that may offer a service to "register" a star in someone's name, generally for a fee, but these are neither sanctioned by the International Astronomical Union (IAU) nor used by professional astronomers. or more information, read this press release.
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Blue Moon is the name given to the second full moon in a month.
Since a full moon occurs every 29 1/2 days, if there is a full moon on the
1st or 2nd day of a month, there is a good chance there will be a second full
moon, or blue moon, that month.
In 1999, there were two blue moons very close together. One was January 31st
(full moons on the 2nd and the 31st) and another two months later on March
31st (full moons again on the 2nd and the 31st). February had no full moon that year.
We then had one in November, 2001 (the 1st and the
30th), and the next one will occur in July 2004.
We won't see two blue moons in one year again until 2018.
A great web site to check for answers to questions like this is at http://image.gsfc.nasa.gov/poetry//ask/askmag.html
There are several questions in the archives at that site about blue
moons, including a table of blue moons through 2028.
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NOAO does not keep track of unexplained phenomena in the sky, so I cannot tell you for certain what it is that you saw. However, there are several possibilities:
First of all, it could not be a supernova because they become very bright for weeks to months, not just for a few seconds. Supernovae that are bright enough for the naked eye to see are also very rare.
If the object was moving, there are a few possibilities. If it was near the horizon the object is most likely an airplane with its landing lights on. The brightening and dimming is caused by the plane changing direction. If the object is high in the sky it may be a satellite. These are fairly common. If you are interested in determining whether or not you saw a satellite I recommend looking at the website: http://www.heavens-above.com/
It makes predictions as to what you may see, however it isn't perfect and it might not predict a satellite that you may have seen.
If the object is not moving it is most likely a planet or star. When planets, and especially stars, are low on the horizon they twinkle rapidly, often changing color. If you saw a planet, the reason it disappeared is most likely that a distant cloud, which you could not see, covered it. This is rather common and a likely explanation.
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The focal length of a mirror is equal to the focal ratio times the
diameter of the mirror. For example, a 1-meter telescope that is
f/8 would have a focal length of 8 meters.
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This area of research has a long history, since a record of tree growth is found
in the thickness of the rings seen in a cross-section of a tree trunk. In
addition, the proportion of Carbon 14 contained in trees is another proxy
indicator of solar activity.
There have been many studies of the variation of these quantities over the past
20,000 years which reveal temporal periods that are also known to exist in the
solar activity cycle. However, the physical mechanisms linking sunspots and tree
growth are poorly understood. The mechanism linking sunspots and Carbon 14 is
fairly well-established to be the modulation of cosmic rays by the solar cycle.
I am not up to date in this area, but here is a review volume from 1991 which
has articles which may be useful:
"The Sun In Time" --CP Sonett, MS Giampapa, & MS Matthews, U. Arizona Press.
In particular, the articles starting on pages 360 and 562 are relevant.
You might also consider contacting Charles P. Sonett (one of the editors &
authors of the above book) for more up-to-date info. He can be contacted
starting from the LPL (Lunar & Planetary Lab) web page listed below.
Tree ring web sites:
http://tree.ltrr.arizona.edu/
http://www.enviroweb.org/edf/ishappening/trees/index.html
Radiocarbon web site:
http://www.radiocarbon.org/
LPL:
http://www.lpl.arizona.edu/
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The Earth's magnetic field does help to protect humanity from the effects of the solar wind, and the gusts in the wind that result when a solar flare triggers a
Coronal Mass Ejection (CME). Even though the Earth's magnetic field is weak in
strength, it fills a vast volume of space, and the charged particles in the
solar wind are deflected by the field.
However, the magnetic field does not completely protect us from the effects of
the sun. Some of the electrical particles in the solar wind leak through the
field, primarily in the areas where the magnetic field enters the surface of the
Earth. This occurs near the north and south geomagnetic poles, located in the
vicinity of the geographic north and south poles. In these areas, the solar wind
actually strikes the Earth's atmosphere, causing the auroral displays.
In addition, the force of the solar wind pushes the Earth's magnetic field
around. When there is a large flare, a strong gust in the wind can shake the
magnetic field, and this can disrupt telecommunications, satellites and, in rare
extreme cases, power distribution systems.
For more information, see the web page at: http://www.spaceweather.com/.
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