May 2004 Sky from the Keeble Observatory
Southern hemisphere skywatchers are already seeing two comets
which should grace our early evening skies from mid-May into June.
Both were discovered several years ago, and are now passing through
the inner solar system. They will be visible about an hour after
sunset, and may brighten to "naked eye" visibility.
The first of these, designated C/2001 Q4, is also known as Comet
NEAT, since it was discovered by the Near Earth Asteroid Tracking
program. It will pass quickly through the constellations Canis Major
and Puppis, into Monoceros by May 10, getting progressively higher
above the western horizon at sunset. Look for it in Cancer, below
Jupiter, about 45 degrees above the horizon on the 15th, about an
hour after the sun sets. The tail should be stretching up and to
the left. By the end of the month, it should be above Venus, in
the constellation Lynx, with its tail pointing straight up from
the horizon. Once you find it with binoculars (or naked eye, if
we're lucky) you should be able to track its motion from night to
night. On the 25th it will be close to the Moon on the sky.
The second was also discovered by a research program actually designed
to detect and track near Earth asteroids, this one the Lincoln Laboratory
Near Earth Asteroid Research program. C/ 2002 T7 is thus known as
Comet LINEAR. At month's end, you should be able to find this one
about 30 degrees off the western horizon at about 9:00 pm. It will
be below Jupiter, in the constellation Hydra. By the end of June
it will move into Sextans.
Next month we'll discuss just what comets are.
Lunar phases for May: Full Moon on the 4th; Last Quarter on the
11th; New Moon on the 19th; First Quarter on the 27th. The Full
Moon will be accompanied by a total lunar eclipse, but will not
be visible from North America.
Evening planet watching is still possible in May. After the Sun
sets, you'll see four planets emerge from evening twilight. Closest
to the horizon (and also the brightest) is Venus. Next Mars, Saturn,
and Jupiter high above and a bit south of west. They are all moving
closer to the Sun on the sky, but for different reasons. Venus is
closer to the Sun than Earth, and moves faster in its orbit than
we do. It's catching up, and will pass directly in front of the
Sun in June. Mars, Jupiter, and Saturn are all farther away. We're
pulling around behind the Sun from their perspectives. Venus, Mars,
and Saturn lie on a straight line, which extends up to Jupiter.
They'll set earlier each evening, leaving Jupiter the lone visible
planet for a while. Enjoy them while they're still in the evening
Mercury is in the morning sky, but very close (less than 10 degrees)
to the horizon, so it will be hard to see. Your best bet may be
on the 16th, when the almost new Moon will be just above and to
the right of Mercury.
Looking overhead about two hours after sunset may seem disappointing.
There are no bright stars near zenith. However, there's still lots
Towards the north we see the inverted dipper of Ursa Major almost
at zenith. On a clear night, your binoculars may enable you to see
further than those stars. Almost 3 ½ degrees directly above
Alkaid, the end star of the Dipper's handle, lies M 51 - the "Whirlpool
Galaxy." With binoculars, you'll likely see only a faint smudge.
In a modest telescope it will appear like a faint swirl, with spiral
arms spinning away from the center. You're seeing face-on a galaxy
much like our own Milky Way, though this spiral appears to be the
result of a collision with a smaller galaxy. Starting again at Alkaid,
you'll see Mizar in the middle of the "handle" about 6
degrees to the left. Imagine an inverted triangle with these two
stars at the top. At the bottom point lies another grand-design
spiral galaxy, this one known as M 101 - the "Pinwheel Galaxy."
No sign of a colliding companion here.
Jupiter is in the constellation Leo, about 10 degrees from Regulus
at mid-month. On a moonless, clear night you'll also find a number
of galaxies within about 5 degrees of Jupiter. Imagine the line
from Regulus to Jupiter, and move up at right angles slowly with
your binoculars. In about 3 degrees you'll encounter M 105, a giant
elliptical galaxy, showing no spiral structure.
To the south, about 40 degrees off the horizon, is Spica, the bright
star in Virgo. Higher and to the southeast you should find Arcturus,
in the constellation Bootes. Castor and Pollux are to the west-northwest,
above Mars and Saturn. We bid them farewell until lat fall, when
they will reappear to the east. The plane of the Milky Way nearly
rings the horizon a few hours after sunset, crossing the plane of
the ecliptic near Venus.
For your own monthly star chart, you can direct your web browser
You will find extensive descriptions of what's worth looking for,
and you can download and print a single copy for your personal use.