NOAO >  Astronomy FAQ

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Frequently Asked Questions about Astronomy

  1. How do I name a star after my Mother/Father/Girlfriend/Boyfriend/etc?
  2. I saw a bright light in the sky last night. Do you know what it was?
  3. How can I buy or build a telescope?
  4. How do you determine focal length of a telescope's mirror?
  5. Where can I find images of sunspots?
  6. How do sun spots affect tree growth?
  7. How does the Earth's magnetic field shield us from harmful effects of the sun?
  8. Where can I find the latest pictures of astronomical objects and planets?
  9. Where can I find information about light pollution?
  10. Where can I find information on planets?
  11. Where can I find information about constellations?
  12. Where can I find information about the sun and moon rising and setting?
  13. Where can I find out about asteroids, comets, and meteors?
  14. Where can I find information about black holes?
  15. Where can I find amateur astronomy organizations?
  16. When is the next Blue Moon?
  17. Where can I find information about leap years?
  18. Can the public observe real-time with Kitt Peak Telescopes?
  19. I need to interview an astronomer for a school report.

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1. How do I name a star after my Mother/Father/Girlfriend/Boyfriend/etc?

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. For more information, read this press release.

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2. I saw a bright light in the sky last night. Do you know what it was?

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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3. How can I buy or build a telescope?

Sky & Telescope Magazine
http://www.skypub.com/tips/telescopes/buying.html
Astro Mart
http://63.169.124.5/default.asp
Weber State University
http://physics.weber.edu/planet/telescope.html
Amateur Telescopemaking Journal
http://www.atmjournal.com/index.html
Capella Plans
http://solar.physics.montana.edu/larson/Capella/index.html

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4. How do you determine focal length of a telescope's mirror?

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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5. Where can I find images of sunspots?

Daily digital images of solar activity can be found at the National Solar Observatory's library of digital images:
http://www.nso.noao.edu/diglib/

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6. How do sun spots affect tree growth?

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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7. How does the Earth's magnetic field shield us from harmful effects of the sun?

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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8. Where can I find the latest pictures of astronomical objects and planets?

NOAO Image Gallery
http://www.noao.edu/image_gallery/
Pictures from the Hubble Space Telescope
http://hubblesite.org/
Chandra X-ray Observatory
http://chandra.harvard.edu/photo/
Mars Global Surveyor mission
http://www.msss.com/mars_images/moc/index.html
NASA Goddard's National Space Science Data Center
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery.html

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9. Where can I find information about light pollution?

International Dark-Sky Association
http://www.darksky.org/ida/ida_2/index.html

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10. Where can I find information on planets?

The Nine Planets - A Multimedia Tour of the Solar System
http://seds.lpl.arizona.edu/nineplanets/nineplanets/

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11. Where can I find information about constellations?

Constellations and their Stars
http://www.astro.wisc.edu/~dolan/constellations/constellations.html

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12. Where can I find information about the sun and moon rising and setting?

The National Naval Observatory Data Services
http://aa.usno.navy.mil/AA/data/

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13. Where can I find out about asteroids, comets, and meteors?

http://www.stud.unit.no/~ltheen/meteor/webresources.html
http://impact.arc.nasa.gov/
http://www.maa.mhn.de/Comet/differ.html
http://seds.lpl.arizona.edu/nineplanets/nineplanets/meteorites.html
http://cfa-www.harvard.edu/iau/mpc.html

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14. Where can I find information about black holes?

http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html
http://www.ncsa.uiuc.edu/Cyberia/NumRel/BlackHoles.html

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15. Where can I find amateur astronomy organizations?

Sky & Telescope Magazine
http://www.skypub.com/resources/resources.shtml
Astronomical League
http://www.astroleague.com/
Astronomy Magazine (Register as a user and click on Organization Guide)
http://www.astronomy.com/home.asp

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16. When is the next Blue Moon?

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.

After that there will not be another until November, 2001 (the 1st and the 30th), and then we'll have to wait until 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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17. Where can I find information about leap years?

http://aa.usno.navy.mil/AA/faq/docs/leap_years.html

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18. Can the public observe real-time with Kitt Peak Telescopes?

To address the idea of "real-time" astronomy, the raw data that astronomers take in the course of their observations are in general not very exciting or informative. For example, there are many modes of observation and most of them do not involve an image of the data that is being taken. The science does not take place at the telescope. Observing at a telescope is less than 1 percent of an astronomer's work - the data reduction that leads to scientific discoveries and papers takes many months, if not years of work. Showing raw data (even if there is something to show) does not really give the public a sense of "what astronomers are doing."

It's important to remember that non-interference with the work of the astronomers is key to the success of any public program. Astronomers compete for time on these telescopes, and every minute of the night is spent observing. They will only get a few nights to perform their research. Weather, instrument problems and other difficulties can easily cut their time down further. The wait for more time can be many months to years. The public programs currently offered by the Kitt Peak Visitor Center do not interrupt the astronomers¹ time.

Having the quality of public programs that already exists at Kitt Peak is extraordinary. There is no other large observatory in the world that has programs like the Kitt Peak Nightly Observing Program (http://www.noao.edu/outreach/nop) and the Advanced Observing Program (http://www.noao.edu/outreach/aop)

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19. I need to interview an astronomer for a school report.

Four interviews are available: Buell Januzzi, Pat Knezek, Gregory Rudnick and Janice Lee.

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NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation. Last updated 29 November, 2000.

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