JUNE 1, 1997: Moon near Sun
- Follow the thin waning crescent moon in the dawn sky as it heads for new moon
early Thursday morning. You must have an unobstructed eastern horizon. Observe
with binoculars just before 5 a.m. On Monday the moon will be to the left of
Saturn, and on Tuesday, it will be just to the right of Mercury. By Wednesday
morning, the moon will be too close to the sun to be seen. However, on Friday
evening look for a very thin waxing crescent moon two fist widths above the WNW
horizon. The moon will be only 46 hours old. If you see a bright starlike
object below the moon, you have also caught your first glimpse of Venus, making
its summer debut. More about Venus in next week’s StarWatch. On Sunday,
June 8th, join members of the Lehigh Valley Amateur Astronomical Society
at the Bethlehem Rose Garden Children’s Festival, 1-5 p.m. as they observe
the sun. The Bethlehem Rose Garden is located at Eighth Avenue and Broad
Street, across from Nitschmann Middle School. Comet Hale-Bopp photo packets
from the ASD Planetarium will also be available for purchase.
JUNE 8, 1997: Venus Debuts in the Evening
- This week marks the return of Venus, goddess of love, to the
evening sky. The third brightest object in the heavens, Venus’s
thick carbon dioxide atmosphere, sulfuric acid clouds, and searing
1000 degree F. temperature would make it anything but pleasant for life.
Observing Venus at first may also prove challenging, but once you have made
your initial sighting, successive views will become much easier. During this
week the sun sets about 8:30 p.m. You should be at your observation site no
later than 8:45 p.m. Apartment dwellers who live in upper floors or high rises
with a clear view of the setting sun may actually be at an advantage because
of their extra elevation. The prime ingredients are a very clear sky and a
good western exposure. Note the location of the setting sun. You can begin
observing as soon as the sun has set. Binoculars will prove useful if not
mandatory even though Venus is exceedingly bright. At arm’s length, view
one clenched fist width to the left of the sunset position and about one
fist above the horizon at 8:45 p.m. As the months of summer progress, Venus
will become a much easier target to spot. Clear skies!
JUNE 15, 1997: Low Moon, High Sun
- The bright moon starts the week to the left of Mars and continues moving
eastward among the stars becoming full early Friday evening. You may have
noticed that the full moons in winter appear high in the sky while the full
moons of summer seem to hug the southern horizon. Part of the explanation
lies in the fact that the orbital planes of the moon and Earth are similar.
The difference is only 5 degrees. When the moon is full, it is opposite
to the sun, and the hemisphere that we view is completely in daylight.
In summer the sun is high in the sky, while the full moon must be low.
The reverse is true for winter. The tilt of the Earth’s axis causes the
seasonal extremes which result in a high summer sun and a low sun for
winter. The sun is at its highest position in the sky on Saturday, making
June 21 the longest day of the year and the beginning of summer. In
Australia and other places in the southern hemisphere, June 21 marks
the first day of winter. Skiing anyone?
JUNE 22, 1997: More Light, More Color
- This week about 10 p.m., look for orangy Mars in the southwest, about
three fist heights above the horizon. To Mars’ left will be blue-white Spica,
the brightest star of Virgo, the Virgin. Spica should appear just a tad bit
fainter than Mars. The pair makes for an interesting contrast in colors
which will be suitably enhanced with the aid of binoculars. The reason that
binoculars accentuate color is because they gather more light onto the eye’s
fovea (cones) where visual acuity and color perception are most heightened.
In contrast, the eye’s peripheral vision is dominated by rods which are more
sensitive to low light levels, but do not resolve well or distinguish colors
at all. The secret to seeing color in astronomical objects lies in the quantity of
light which is gathered. Look south to observe a waning gibbous moon above Jupiter
in the predawn hours on Tuesday.
JUNE 29, 1997: Reasons for the Seasons
- Mid-afternoon on Friday, the Earth reaches aphelion, its farthest position
from the sun. The sun’s distance will be about 94.5 million miles. In early
January this distance shrinks to a minimum of 91.4 million miles as Earth
passes its perihelion position. Confused? Don’t be! The seasons are not
the result of Earth’s changing distance from the sun, but rather its axial
tilt to its orbital (ecliptic) plane. If earth’s axis were vertical to the
ecliptic, there would be no seasons. But because our axis is tilted 23-1/2
degrees from the vertical, our northern hemisphere leans in towards the sun
during summer. The sun is higher in the sky and visible for a longer period of
the day. This provides us with more energy and warmer weather, despite our
greater distance from the sun. Go to Astronomy links, then to Misconceptions,
and finally to Earth on the web page below to find out more about the seasons.