By Richard Hall
All times are adjusted for daylight saving
The chart shows the
heliocentric orbital positions of the planets for September 1st 2008. The planets are orbiting in an anti-clockwise
direction and smaller images show the positions of the inner planets for the 15th. The orbits of the inner planets,
Mercury, Venus, Earth and Mars, are to scale.
Planets beyond Mars are placed in shells. These are Ceres, Jupiter, Saturn, Uranus,
Neptune, Pluto, and Eris. A line drawn
from the Earth through the Sun reveals the constellation of the Zodiac that the
Sun is moving through. Because the Earth
rotates in an anti-clockwise direction planets to the right of this line rise
after midnight and are
therefore morning stars. Those to the
left are evening stars.
|
MERCURY - makes its best evening appearance of 2008 in
early to mid-September. The planet
reaches greatest elongation on the 11th when it will be 27 degrees
east of the Sun. On this date it will be
seen as a bright star (magnitude +0.1) in the west that will be setting over
two hours after the Sun. In a telescope
it will look like a tiny first-quarter moon, phase 57%, 7.0” in diameter. In mid-September it will begin to move back
towards the Sun and then reaches a stationary point on the 24th. By this date its diameter will have grown to
9” and its phase will have become a crescent (phase 29%). However, by this time it will be setting in
twilight only 40 minutes after the sun.
Before the end of the month the planet will be lost from view. |
 |
VENUS - is the brilliant evening star (magnitude -3.8)
that can be seen in the west after sundown.
At the beginning of the month it sets just under 2 hours after the sun,
by the month’s end it will be 2.5 hours.
In a telescope it will be seen to have a slightly gibbous phase (90%),
11.3” in diameter.
|
 |
MARS
- continues to hover in our western evening sky
setting about two hours after the Sun. The
planet is steadily traveling eastward through the constellation of Virgo. At magnitude +1.7 Mars is now at its
faintest. Its telescopic diameter is
only 3.8”.
|
|
JUPITER
- is in Sagittarius and passes directly overhead
in the evening. At magnitude -2.4 it is
second in brightness only to Venus but, unlike Venus, Jupiter is visible for
most of the night. Of all the planets
Jupiter is the best placed for observing and its four largest moons are visible
in binoculars. In a telescope the
orbital motion of the moons around the planet, transits, eclipses and other
phenomena can be easily observed. The
planet’s telescopic diameter is 41”.
Jupiter is stationary on the 8th of September.
|
 |
SATURN - is in conjunction with the Sun on September 4th
and will not be visible until the end of the month when it may be glimpsed in
the eastern dawn twilight. Saturn is in Leo
and its magnitude, when it reappears, will be +1.0.
|
 |
URANUS
- is in the constellation of Aquarius and reaches
opposition on the 13th. On
this date its distance from the Earth will be 158.77 light-minutes. At magnitude +5.7, Uranus is just visible to
the unaided eye from a dark sky site. In
a telescope it will be seen as a tiny greenish disk 3.7” in diameter.
|
 |
NEPTUNE - is in the constellation of Capricornus and is
above the horizon for most of the night.
At magnitude +7.8 the planet is visible in binoculars and, in a
telescope it will be seen as a tiny bluish disk 2.3” in diameter.
|
 |
PLUTO - can be found in the constellation of Serpens
Cauda but, at magnitude +13.9 it is visible only in large telescopes. Pluto is stationary on the 9th
|
CONJUNCTIONS & OCCULTATIONS
Conjunctions and occultations
visible from New Zealand for this month are listed below. A conjunction occurs when two celestial objects come close together in
the sky. An occultation occurs when one
celestial object moves in front of another. The hour given is the time of
closest approach for a conjunction or the approximate time of disappearance of
one object behind another in the case of an occultation. The exact time of an occultation, and its
duration, will depend upon the observer’s latitude and longitude. Phase gives the direction that the
illuminated side of the moon is pointing. The phase is pointed west between new and full moon, and east after.
7th Antares 0.3o north of the Moon (3pm, quarter west)
12th Venus 0.3o north of Mars (9am)
13th Neptune 0.8o south of the Moon (2pm, gibbous west) 24th Mars 2o south of Spica (7am) |
