StarWatch: Moravian College Astronomy
AUGUST 3, 1997: Observing Meteors
- Now that your meteor gear is assembled (see last week’s StarWatch), you’re
ready to try catching some Perseids. Pick a location with good horizons, and
set up facing the northeast. Perseid meteors will appear to radiate from the
constellation of Perseus, the Hero, which becomes prominent after midnight.
Plan on at least 2-3 hours of observing. For the first hour, just watch.
Around midnight Perseids seem to diverge from a location in the NE, about a
third of the way up in the sky. They move swiftly; some are very bright, and
many leave trains, an afterglow of luminescent air after the flash. Keep
your own hourly counts. Break for no more than 10 minutes/hour of observing.
Rates increase after midnight as the Earth rotates us forward so that we plow
into the bits of cometary debris which result in creating Perseid meteors.
Perseid rates will be greatest on the morning of August 12. Photographing
the Perseids next week...
AUGUST 10, 1997: Photographing Meteors
- Perseid meteors will fly after midnight on the mornings of Tuesday, August 12th
and Wednesday the 13th, and in lesser amounts thereafter. Moonset on the 11th is
at 11:30 p.m., and 1:12 a.m. on the 13th. To photograph the Perseids, use an SLR
camera, 50 mm lens set at F/2.0-F/2.8, and a relatively fast film such as Royal Gold
400 for color or Tri-X for b/w prints. A tripod and cable release are necessary to
control exposure times and motion. Set your shutter speed to bulb, "B" and with
your cable release, lock your shutter open for periods of no more than five
minutes. Point your camera straight up. You may need a hair dryer to warm your
lens occasionally between shots so that dew does not condense on the glass. For
point and shoot cameras, contact Tim Miller at Dan’s Camera City--610-434-2313.
Some Pentax models and others have a "B" setting, but many will not be adaptable.
AUGUST 17, 1997: Day of the Full Moon
- The moon begins the week nearly full, but technically doesn’t reach the full
phase until 6:55 a.m. EDT Monday. By that time the sun has risen over the Lehigh
Valley. So Monday is the date of full moon, even though for most of us who keep
more civil sleeping routines, the moon was closer to being full on Sunday evening.
In order for the moon to be technically full, it must be opposite the sun in the
sky. Whenever this moment occurs, the moon is considered full at all locations
throughout the world. "Lunatics," skywatching in California on Monday morning
will be able to witness the exact moment of full moon at 3:55 a.m., PDT. Catch
Saturn just above a waning gibbous moon around midnight on Thursday.
AUGUST 24, 1997: Planets Don't Twinkle
- If you saw Saturn near the moon late last week, you may have noticed an even
brighter "star" in the south. That was the planet Jupiter. Jupiter is visible
low in the southeast right after dark. If you compare Jupiter to any of the
other stars in the sky, you should notice two important things. Its brightness
is impressive, and Jupiter is shining with a steadier light. These two
observations are the sure give-away for any of the traditional planets seen
by the ancients. Planets shine with a steady light because, unlike stars,
they can be magnified with telescopes into disks. No matter what the power,
stars will always appear as pinpoints of light. The motion of the ocean of
air that we live under is much more effective in causing point sources to
twinkle than light coming from magnifiable disks. Hence, planets shine with
an unwavering light, while stars twinkle. More about this in two weeks.
AUGUST 31, 1997: Moon, Venus, and Mars Pair Off
- Happy First Birthday StarWatch! Readers suggestions regarding this weekly
sky bulletin are always appreciated and can be left as a phone message at
610-820-2204 or e-mailed to email@example.com. The moon is new on Monday
evening, but by Wednesday, it begins to enter the scene as a thin crescent,
low in the west. Venus is far to the moon’s left, but the moon quickly
catches up to the Goddess of Beauty, and the two make a striking photographic
pair in the darkening evening sky by Friday. On Sunday, the moon and Mars
are now pairing off in an even darker sky. Remember how Mars and Comet
Hale-Bopp dominated the heavens in the spring? Since then, Earth and Mars
have moved much farther apart. This has caused the Red Planet to appear a
little over 8 times fainter than it was in late March.