What's Up?
By Bernie
Reim This month opens with
a trio of neighboring planets playing tag in our western
evening sky shortly after sunset. We are in the middle of
summer now, and the nights are getting longer again so we
can enjoy more of its wonders. The night sky always has
much to offer, but many of us simply don't take the time
to appreciate our connections to the universe and how
that can greatly improve the quality of our daily lives
as we put that knowledge and imagination into practice.
Two meteor showers
will grace our skies this month, including the famous
Perseids. A short period comet should also get bright
enough to be seen with a pair of binoculars by the middle
of August. Look low in the
western sky shortly after sunset, and you will see that
Mars has already passed Saturn. Venus will also glide
below Saturn about a week later. These three planets will
put on a display of beautiful celestial geometry all
month long. On August 10, the three will form a near
isosceles triangle, with two of the sides nearly equal,
with brilliant Venus anchoring the bottom, orange Mars to
the upper left, and golden Saturn to the upper right.
This triangle will fit into a 7 degree-diameter circle.
Then continue watching this ever-changing geometry lesson
as a slender waxing crescent moon joins the trio on the
evening of Thursday, August 12, the night that the
Perseid Meteor Shower will peak. There will even be an
earlier meteor shower this month, the Northern Delta
Aquarids, peaking on Sunday night the 8th. The comet that
created these meteors has long since taken on a different
orbit or crashed, unlike Comet Swift-Tuttle, which causes
the Perseids each year. Although its numbers will not be
nearly as prolific as the famous Perseids, the Northern
Delta Aquarids originate from a very interesting place in
our night sky. The radiant of this meteor shower will be
just above the first magnitude star named Fomalhaut in
Piscis Austrinus, the Southern Fish. Fomalhaut became
famous in November of 2008 when the first planet to be
seen directly with visible light as imaged by the Hubble
Space Telescope, was found orbiting Fomalhaut. Named
Fomalhaut B, this planet is located 10 billion miles from
its parent star, which is 10 times the distance to
Saturn, takes 875 years for one orbit and is no more than
3 times the mass of Jupiter. If it were any more massive,
it would have destroyed the vast dust belt that surrounds
Fomalhaut. About 20 billion miles in diameter, this great
dust ring is 2 billion miles wide, or about 25 times the
earth-sun distance. This shows how tremendously balanced
and delicate this giant dust ring really is. It was
suspected for 8 years that a planet might be orbiting
Fomalhaut because of this dust ring, but it wasn't proven
until November of 2008. At that time, only about 300
other planets had been found in other solar systems, but
this was the first one seen directly without having to
infer its presence through other means of detection. Now
we know of nearly 500 exoplanets already. Fomalhaut is
twice the mass and diameter of our sun and located only
25 light years away. It is a very young star, only about
200 million years old. That is less than one twentieth
the age of our earth and our sun. That is about the time
the first dinosaurs appeared and the last supercontinent,
Pangaea, started breaking up. Fish have existed in our
oceans for more than twice that time. Its name means the
mouth of the fish or whale in Arabic. The famous Perseids
will be favorable this year, because there will be no
moon to interfere with this tremendous, yet totally
silent, celestial fireworks display. You can expect up to
100 meteors per hour from a dark sky sight before dawn on
the morning of Friday the 13th. You can expect about half
that many the night before and after that date. Look low
in the northeastern sky in Perseus the Hero to catch the
radiant of these prolific meteors. Caused by Comet
Swift-Tuttle, these tiny, sand grain-sized pieces of
comet dust will be crashing into our upper atmosphere at
nearly 40 miles per second, leaving brilliant streaks of
light. There will be a short
period comet, named 10P/Tempel that should be visible by
the middle of August with binoculars or a small
telescope. It orbits the sun every 5.4 years, looping
from just inside the path of Mars out to Jupiter's path.
By comparison, Halley's Comet takes 76 years to make one
orbit and is not due back until 2062, although you can
see tiny pieces of this famous comet burn up in our
atmosphere as meteors twice each year, on May 4th as the
Eta Aquarids, and on October 21 as the Orionids. Comet
10P/Tuttle should reach 8th magnitude or brighter and be
visible by 1 am in the constellation of Cetus the Whale
in the southeastern sky. This comet reached perihelion,
or its closest approach to the sun back on July 4. Try to
catch this ancient relic from our solar system's original
formation this month, because you will have to wait 3
more orbits, until 2026, for its next favorable
apparition. The other 2 gas
giants, Uranus and Neptune, are also interesting to see
this month, but you will need binoculars or a telescope
to really appreciate these last two planets, representing
one quarter of all the planets in our "new" reduced solar
system. Uranus should be easy to find, because it will be
just 2 degrees to the right of brilliant Jupiter in
Pisces, now rising before 10 pm. However, Uranus will be
nearly 9 magnitudes, or about 3000 times fainter than
Jupiter. Our 7th planet was discovered back on March 13
of 1781 by William Herschel. It was actually first
discovered by John Flamsteed back in 1690, but he thought
it was just a star in Taurus, so he did not get any
credit. If he would have kept watching it from night and
night, he would have noticed that it moved a little, so
that would preclude it from being a star. Neptune,
mathematically predicted to exist in 1845 by John Couch
Adams in Cambridge and LeVerrier in Paris, but first
observed by the German astronomer Johann Galle on Sept.
23, 1846 will have finally completed one orbit around the
sun since that time. Neptune is the only planet in our
solar system that was first shown that it had to exist
mathematically and then it was actually found to exist,
providing dramatic proof of Newton's laws. Neptune was
actually first seen by several other astronomers
including Galileo himself back in 1612 and 1613, but
again it was mistaken for just a star. The beautiful blue
disk of Neptune is now in almost the same place in the
sky when it was first discovered 165 years ago.
August
5. Neil Armstrong,
the first human to set foot on the moon, was born on this
day in 1930, the same year that Clyde Tombaugh discovered
Pluto. August
9. Venus passes 3
degrees south of Saturn tonight. New moon is at 11:08
pm. August
11. Asaph Hall
discovered Deimos, one of the two tiny moons of Mars on
this day in 1877. He discovered Phobos, the other moon of
Mars on August 17, 1877. August
12. The Perseid
meteor shower peaks. August
13. The moon
passes just south of Saturn, Venus, and Mars
tonight. August
16. First quarter
moon is at 2:14 p.m. August
22. On this day in
1963, the X-15 set the world altitude record for a winged
craft at 354,000 feet or 67 miles high above the earth.
August
24. Full moon is
at 1:05 p.m. This is also called the Sturgeon, Grain or
Green Corn
Moon.
Northern Stars
Planetarium and Educational Services
August
3. Last quarter
moon is at 12:59 a.m. EDT. The Messenger spacecraft was
launched to Mercury on this day in 2004.
Bernie Reim
berniereim@masiello.com
Bernie Reim is an amateur astronomer who writes a monthly
astronomy column for several newspapers throughout Maine.
Including: The
Portland Press Herald,
The
Kennebec Journal,
The
Morning Sentinel,
and the York Weekly. He also teaches astronomy lab courses
at the University of Southern Maine.
Fairfield, ME
(207) 453-7668
info@northern-stars.com