OverSky for March 2003: THE OLD, THE COLD AND THE DIRTY
- OverSky for March 2003: THE OLD, THE COLD AND THE
posted by Erich Landstrom, NASA JPL Solar System
While waiting one night for a meteor shower to peak,
my friend shared a true story: a few years back, she
was at her favorite stargazing, far from any light
pollution, with a friend who hadn�t been under such
dark skies in a while. He was excited to set up his
telescope, but was annoyed at the one cloud that
arched across the sky and refused to budge, blocking
We laughed at his frustration. That �cloud� wasn�t
going anywhere any time in the next three billion
years. That �cloud� was our Milky Way Galaxy, made up
of millions of star systems, star clusters and
nebulas. With so many stars, the Milky Way is over
600,000 trillion miles wide. In fact, we are looking
at the Milky Way from the inside because our solar
system is a part of it. The light from so many stars
so far spread out blends together. Our eyes are not
sharp enough to pick out the individual stars,
creating a faint, hazy appearance of a milk-white arch
that rings around the sky. April is the last month to
see the part of the Milky Way that stretches behind
the winter constellations. Away from city lights under
clear, dark skies, look to see it from the north in
Perseus to the south in Pyxis, at the top of Taurus
and the feet of Gemini and through Auriga, and between
the winter triangle of Orion, Canis Major and Canis
Minor. (Don�t worry if you miss it this month -- you
have until the Milky Way collides with the Andromeda
Galaxy 3 billion years from now. Even then, they merge
slowly, over about 1 billion years, to form a
non-spiral, elliptical galaxy.) But any bright light
is enough to spoil your view and hide the galactic
glory of the Milky Way.
Our view of Milky Way Galaxy is blocked, though, by
clouds of different type: intergalactic dust clouds.
The light and more importantly the heat from distant
suns are absorbed. Sensing that heat would allow
astronomers to detect discs around other stars where
planets may be forming, and provide valuable
information about the early life of the universe.
Nicknamed �the Old, the Cold, and the Dirty,�
(referring to the oldest, coldest and most
dust-obscured objects and processes in outer space)
these are the targets of the Space Infrared Telescope
Facility (SIRFT). Launch of SIRTF is scheduled for
Tuesday, April 15, 2003, at 4:34:07 AM EDT from Cape
Canaveral. SIRTF compliments the Hubble Space
Telescope. Both belong to NASA's Great Observatories
Program, each of which studies a different part of the
spectrum; Hubble shoots pictures in visible light,
Chandra takes X-ray images. Infrared light, invisible
to the human eye, is typically absorbed by Earth's
atmosphere and therefore ideal for an Earth-trailing
space telescope. More information about the mission is
Old, cold and dirty also describes comets. Comets are
interplanetary icebergs, and as a comet nears the Sun,
dust mixed in with the ice is released. A meteor
shower occurs as Earth transits through the tail of
dusty debris dispersed by a comet. Before dawn on
April 22nd the Lyrid meteor shower reaches its peak.
The meteor shower is associated with the orbit of
Comet Thatcher, which was first recorded in 687 B.C.
In April 1803, 700 meteors per hour were seen.
However, April 2003 is expect to be more modest, with
a maximum of 15 meteors per hour
Interested observers should look northeast after
midnight. The Lyrid meteors are so named because they
appear to emanate from the constellation of Lyra the
Harp, home to the 3rd brightest star of the sky.
Unfortunately the last quarter Moon rises at almost
the same time as Lyra and its light will interfere
with this year's display.
LUNAR ALMANAC APRIL 2003 (All times are Eastern Time)
April 1: New Moon
April 4: Moon at apogee (406,209 km)
April 7: Moon near Saturn
April 9: First Quarter
April 10: Moon near Jupiter
April 16: Full Moon
April 17: Moon at perigee (357,156 km)
April 23: Last Quarter, Moon near Mars
Tip: The full moon's diameter measures about 1/2 of
one degree in the night sky.
SOLAR ALMANAC April 2003 (All times are Eastern at the
80 deg. N. longitude of West Palm Beach. Add 20
minutes to each time for each 5� west.)
Apr. 1: Sun Rise: 6:11 AM EST, Sun Set: 6:37 PM
Apr. 14: Sun Rise: 6:57 AM EDT, Sun Set: 7:43 PM
Apr. 28: Sun Rise: 6:44 AM EDT, Sun Set: 7:50 PM
MERCURY materializes out of the dusk at sunset,
shining at mag. -1.4 as April starts. But midmonth is
has faded to mag. -0.5, but has climbed 20 degrees
above the horizon. Using binoculars, look low in the
west about 30 minutes after sunset.
JUPITER (mag. -2.1) outshines the surrounding stars of
Cancer, standing high and bright in the southwest in
the early evening.
SATURN (mag. +0.1) shines at the tips of Taurus and
the toes of the Twins in the south after evening
twilight, visible as the yellow �star� over Orion's
head at sunset and setting around midnight.
VENUS is so low in the pre-dawn sky that it is almost
impossible to see until the end of April.
MARS rises around 2 AM in the southeast. As it moves
from Sagittarius into Capricornius, it continues to
get brighter until it doubles in magnitude to +0.5.
For news on space exploration with the "science giant"
Erich Landstrom, listen to a live broadcast of SCIFI
OVERDRIVE Monday mornings at www.scifioverdrive.com
over the Internet! Our guests on Apr. 10 and 17 will
talk about SIRTF and the Gravity Probe B. Free
telescope viewing will be offered if the weather
permits at the following dates and places: on
Wednesday, April 9th at the main public library in
West Palm Beach on Summit Blvd., on Thursday, April
10th at the public library in West Boynton Beach on
Jog Rd., and on Friday, April 18th at Sugar Sand
Community Park at Military Trail & Palmetto Park Rd.
in Boca Raton.
Erich Landstrom, NASA JPL Solar System Educator
Solar System Educators Program http://www.ssep.org
[Hands-on teacher training workshops sharing NASA's
missions of research, discovery and exploration!]
Science fiction & science fact stranger than fiction.
Listen Monday mornings on http://www.SCIFI-OVERDRIVE.com
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