What was that Bright Light in the Sky?

Question: On September 6, in Glendale AZ, at 20:45 hrs, my husband and I thought we saw a satellite in the North Sky.  (We are sky watchers.)  We agreed it was too bright.  Then it went in circles, then east and west, sometimes fast, slow or still, u-turns, bobbing, even a kind of dancing.  Our neighbor saw it.  Her neighbor saw it Sept 5th. A group of our neighbors said they watched it a month earlier.  I contacted the National UFO Network (NUFORC) and they said it was Vega.  No way.  This has me bugged.  What do you say?  — Kare

Answer: There is really no way to know exactly what it is you saw.  Aircraft would be the most likely answer given the behaviour your note.  Other options require more complex scenarios.  It is often useful to keep Occam’s Razor in mind when evaluating situations such as this.  In the end, it is usually the least complex answer that is the correct answer.

Jeff Mangum

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How to Determine the Relevant Date for a Star Chart

Question: How can I find the date from a given star-chart?  – Anand

Answer: In the following I am going to assume that you are using a star chart appropriate for the mid-latitudes in the northern hemisphere.  The easiest way to determine what date a particular star chart refers to is first know the approximate dates that a few bright stars transit at midnight:

  • Pollux: January 15
  • Regulus: February 22
  • Arcturus: April 25
  • Vega: July 1
  • Deneb: August 1
  • Aldebaran: December 1
  • Capella: December 10

If your star chart has any of these stars near transit then the date for that star chart is likely very close to the relevant date listed above.

Jeff Mangum

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What Caused the Bright Crater I Now See on the Moon?

Question: Sir Took a picture of the Moon a few days ago and in the lower right hand [corner] a crater was very bright. Was the Moon hit recently?  – Bill

Answer: I am not aware of any recent collisions between our Moon and an object that would create a sizeable crater.  Note, though, that existing craters on the Moon can appear brighter or dimmer as a function of how they are illuminated by the Sun.  For example, a crater can appear quite shadowed one day, then a few days later, when the Sun’s illumination angle has changed to be more direct, appear quite a bit brighter.  This may explain your observation.

Jeff Mangum

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Motion of the Stars in the Night Sky

Question: Why do we see the same stars every day of the year in there same location when we orbit?  No way does the Cosmo’s move with us.  – Mike

Answer: In fact, the stars that one can see in the night sky on any given night change as the Earth moves along its orbit around the Sun.  You can test this yourself by noting the location of a bright star on one night at a specific time.  Come back a few weeks later at the same time and note the position of the same bright star.  You will find that the star has moved a bit to the west from its previous location.  This is due to the fact that the Earth has moved a bit along its orbit, which presents a somewhat different view of the stars in our night sky than it did previously.  If you wait an entire year between star position measurements, though, you will find that your star has come back to the same spot.

Jeff Mangum

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When Does the Earth’s Prime Meridian Line Up With the Celestial Meridian?

Question: On what date and time to the nearest second (in the past) has earths prime meridian directly lined up and faced the
“celestial meridian” and I am talking about using the “equatorial coordinate system”

Definition for “Celestial Meridian” which I am using from Dictionary.com below:
“In the equatorial coordinate system, a great circle on the celestial sphere passing through the celestial poles and the vernal equinox. It represents the zero point for the horizontal coordinate in this system, having a right ascension of 0 hours.”

I might have thought it was vernal equinox but that happens once every year but the earth doesnt rotate exactly 360 degrees per year so the prime meridian on earth would not always line up. So thats not my answer so I cant just look up Vernal equinox dates on the web.
Its might happen every 4 vernal equinox but not sure. That still would not give me a date which I am looking for.

Prefer UT time or Julian date but anything would help.
Does the date time I am looking for even have a unique name for it?

– Steve


Answer: The Earth’s “prime meridian” is the great circle which passes through the Earth’s poles and represents the start of the longitude coordinate system, or zero-degrees longitude.  Comparing that to the definition you have given above for the celestial meridian, I would say that these two meridians line up once each day.  The exact time in a day that the prime meridian aligns with the celestial meridian is determined by the difference between a solar and sidereal day, or about 4 minutes.

Jeff Mangum

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What Are Those Two Bright Lights on the Western Horizon?

Question: On July 15, 2015, observing from Las Vegas, Nevada, there are 2 objects (Low) in the Western sky. One is bright the other dim. Are they Venus and Jupiter?  – George

Answer: Yes!  Venus, the brighter of the two, is to the south (left when facing west) of the other bright guy, Jupiter.

Jeff Mangum

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What is that Bright Object in the Western Sky After Sunset?

Question: What bright light is in nepa’s sw sky at 30degrees above the horizion at 9:15 edt.  – Tom

Answer: Although I don’t exactly know what location you are observing from, I suspect that you are seeing Jupiter and Venus, which are both currently visible on the western horizon after sunset.

Jeff Mangum

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Are UFO’s Real?

Question: What is your opion of UFO’s  observed from ground surface and those observed from space stations and shuttle flights?  I have heard the there is a “Coloney” on the side of the moon we never seen.  Your opinion?  – Kevin

Answer: The fact is that there has never been a confirmed sighting of a UFO that has also been confirmed as evidence of an extraterrestrial presence.  Conspiracy theories are usually based on little or no hard evidence, and are often simply designed to entertain.

Jeff Mangum

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Why Do Stars Appear to Move in the Night Sky?

Question: Why do the stars in the sky appear to orbit? – Ariana

Answer: I think that you are asking why stars appear to move through the night sky from east to west in tracks that appear to be centered on the North Star.  These apparent star tracks are in fact not due to the stars moving, but to the rotational motion of the Earth.  As the Earth rotates with an axis that is pointed in the direction of the North Star, stars appear to move from east to west in the sky.

Jeff Mangum

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Identifying Strange Sounds Received by a Radio

Question: I received a radio wave with my homemade antenna that it sounds like a motorbike, like a Harley Davidson. Which type of signal it could be? it could be about the sun or the earth magnetosphere? It’s for a school presentation. Thanks.  – Gerard

Answer: The source of a radio signal depends upon the frequency that you were tuned to (among other things), but I suspect that if you were using a standard radio frequency (a few 10s of mega-Hertz) that what you received was a man-made transmission of some kind.  There are a number of places on the web which can help you identify man-made radio broadcast noises.  For example, W2SJW’s collection of strange radio noises contains numerous samples of man-made radio noises.  You might try listening to some of these sound samples to see if they sound like what you are hearing.

If you think that these might be sounds produced by ionospheric effects, you might try the Earth Sounds web site (although this web site appears to have fallen into disrepair…).  There are only three sound samples listed, and none of them sounded like a “motorbike”.

Jeff Mangum

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