Expert: Tom Whiting - 9/24/2004

Question
Hello Tom!

I'll get right to it! I live in Ottawa Canada, and as of late, my family and I have observed a strange red bright (twinkling) object in the sky after 7:45pm in the West (until around 9:45pm when it sets beyond our field of vision (it's hilly here). I hope that's specific enough. It's bright enough to overcome the light pollution, and can be seen very easily. Upon using binoculars and a telescope (not really the best), we observed that it changes colours! From red, to fuscia, to green, to cyan, then it cycles back again. I wasn't able to get a close look of it with the telescope, as I need a good telescope with a good tripod - mine takes a steady hand.
We would appreciate knowing what it is!
Thank you!
Emilie

Answer
Hi Emilie,
I would have answered sooner, but the AllExperts website
has been down for repairs.

You are seeing the bright, zero magnitude star,  Arcturus
(Alpha Bootis)  in the west; same star you were seeing high in the south, almost at your zenith,  just after darkness falls around 11 pm, in late May.  (Brightest star in the constellation Bootes, in the west).

All twinkling, colour change in stars, the red sunset, the
orange rising moon, etc....along with halo's, rainbows, mock suns, green flash, sun pillars, etc.  are all atmospheric (the air)
phenomena.  If  we, the Earth, did not have an atmosphere,
no stars would twinkle, or appear to change color, no red sunsets, no orange rising moons, etc......objects would be
bright, no colour change, and same intensity (no twinkling), right down to the horizon, just like standing on the moon.

Since the twinkling and colour change is NOT inherent
in the star, but part of our atmospheric phenomenon, it doesn't matter if you use optical aid or your naked eye,
the twinkling / colour change, appearance will be the same.
The twinkling and colour change will be even more violent
if you add in light pollution, cloudy haze (high moisture content in the air above you), and the jet stream overhead,
which it has been over central Canada for the past 4 or 5 days.

Astronomers speak of "seeing" and evidently the seeing
in your area has been very poor this past week....doesn't matter how clear or transparent the sky is, you can still
have very poor seeing if the core of the jet stream is right
over your location.  It affects resolution in a scope, the
ability to split two close pin-points of light, say a close double star, or planetary detail, thus the astronomer is limited
to low power eyepieces, and doesn't even consider going up
to moderate or high power, because the higher powers will
just magnify the poor seeing conditions.

Just as Arcturus is setting in your western sky around
9:30 pm, check out Capella, another bright zero magnitude
star, just rising in your northeastern sky....it will exhibit the
same twinkling/colour change until it climbs above about
30 degrees elevation, if you are experiencing poor seeing
conditions.
Hope all this helps, and feel free to contact me directly at
bwhiting@velocity.net
if you need further astronomy questions answered.
Clear Skies,
Tom Whiting
Pres...ECMOG
Erie, PA

Also, please visit our astronomy club website
for great pictures of my new 30 inch portable scope...at
http://www.velocity.net/~bwhiting/


FOLLOW UP-
Oh, and BTW, Arcturus....nicknamed Job's Star...is
the only REAL star mentioned in the Bible (other than the sun, of course...check  Job 38:32...
just as the open star cluster, the Pleiades
(7 sisters, M-45, Suburu...other names) is the only open
star cluster mentioned in Bible,  in Job 38:31.
(The Pleiades are often thought to be the "little dipper"
by the uninformed....it isn't...it's an open star cluster in Taurus...the real Little Dipper starts at Polaris, the North Star, 50th brightest star in our night sky.)

FWIW
Tom Whiting


You are very welcome Emilie...
feel free to ask me any astronomy question anytime,
as I am retired so home most of the time.
(Except this weekend...we are going up to Toronto
to visit the CN tower, have dinner up there, and watch
a taping of the Red-Green show across the street at the
CBC studio....we are big Red-Green fans down here).
Clear skies,
Tom Whiting
Erie, PA