|
 What's
in the Skies This Month
meteor showers
There
are no major or moderate meteor showers this month.
Tips on how to
watch meteor showers
THE NAKED EYE PLANETS
 Mercury
Mercury is going to be quite easy to observe throughout September, the
best opportunity presenting itself in very bright dusk skies only 30
minutes after sunset through the first two weeks of September.
Since the elusive innermost planet is just past its greatest elongation
from the sun you might spot it right on the WNW horizon if binoculars
are used. The only way that you might find it is to observe with
an unobstructed western horizon and begin scanning about 30 minutes
after sunset, right along the horizon from WEST toward NW.
Venus
The
brightest of the planets is now an "evening star" and rising just after
the sun a bit later each evening throughout September. Watch as this
beautifully bright planet slowly attains a higher altitude above the
western horizon each night this month. At magnitude minus 4.8 Venus is
the brightest object in the sky except for the sun and moon. In a
telescope, Venus grows nearly double during September and presents a
"gibbous phase", nearly fully illuminated as seen from Earth.
 Mars
Mars is about to leave us for about two years, now very low in the sky
at sunset and setting at the end of astronomical twilight in the western
sky. Mars is tiny when viewed in telescopes, and appears as a
reddish "star" just to the left (south) of brilliant Venus on September
1st and to the right (north) of Venus by September 16th.
Jupiter
Mighty Jupiter still looms bright in evening skies, south of overhead
for northern latitudes as the skies darken this September. The planet
has been moving eastward in retrograde motion the past month, but look
for this to stop and the large yellow orb will appear to reverse its
course this month and appear to once again move eastward through the
distant stars. The largest of all solar system planets, Jupiter is
poised beautifully for low power wide field telescopes in the "handle of
the teapot" of Sagittarius, amidst the rich stars near the center of our
own Milky Way Galaxy.
 Saturn
After
hiding in the glare of the sun during solar conjunction (Sept. 4), the
magnificent ringed planet once again makes its debut in morning skies in
late September. Look for a beautiful pairing of the waning
crescent moon and bright Saturn just as dawn breaks about one hour
before sunrise on the morning of September 27, when the two will be very
close together on the eastern horizon. Saturn's rings are now nearly
edge-on as seen from Earth, angled only four degrees and shrinking.
By winter the edge-on incredibly thin rings will be so aligned to Earth
that only the largest telescopes will be able to detect them at over 800
million miles distant.
phases
of The moon
   
Sept. 3 Sept.
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Sept. 18
Sept. 25
sky
watch news
See Trio of Planets at
Sunset
By
Joe Rao
-
SPACE.com Skywatching Columnist
 The
planet Venus passed conjunction with the sun on June 9 and is now
emerging into view in the western evening sky. But it will be a long and
tedious process. Even by the end of September this planet will still very
low at dusk.
Look for Venus just as
evening twilight fades, but don't wait too long, for it will set only about
an hour after sunset. Scan just above the western horizon about 20 to 30
minutes after the sun goes down. Binoculars will certainly help you pick out
Venus' silvery spark from the still-bright sky. As the season grows cooler
Venus will slowly rise higher, until it shines as a brilliant "evening star"
in the twilights of winter.
But Venus is currently
not alone, for also nearby are the planets Mercury and Saturn.
Over the past week
these three planets have been clustered rather closely together.
Unfortunately, their close proximity to the sun caused these planet
bunchings to be visible only with difficulty against the bright backdrop of
evening twilight. They are still relatively close together this week,
although all three are so very low to the western horizon and so deeply
immersed in the bright sunset glow that it is debatable that — aside from
Venus — that the other two planets will be observable.
Your best bet is to
use binoculars and scan near the western horizon about 15 to 30 minutes
after sunset.
Swap in Mars
In September, Saturn
disappears into the fires of sunset and is replaced in the planet trio by
Mars. So it will then be Venus, Mercury and Mars that will spend much of
September tightly grouped together. Unfortunately, their proximity to the
sun will continue to be a problem, so they'll continue to be visible only
with difficulty against the bright backdrop of twilight.
Using binoculars and
scanning the horizon somewhat to the south of due west about 15 to 30
minutes after sunset on Sept. 1, you just might be able to pick up Venus,
Mercury and Mars forming a right triangle. And below and to the left of this
planet trio will also be a narrow crescent moon just 2.1 days past new.
Viewers in the
southern U.S. will have a bit of an advantage in that this group will appear
a bit higher above the horizon.
Planet shuffles
On Sept. 7, the
Venus-Mercury-Mars grouping will resemble an isosceles triangle, with the
Mars-Mercury and Mars-Venus sides measuring about 2.5 degrees in length and
the Mercury-Venus side about 4 degrees. And located about 10 degrees
(roughly the width of your fist held at arm's length) to the upper left of
the triangle will be Spica, the
brightest star
of the constellation Virgo.
Venus and Mars will be
separated by only 0.3 degree (less than the apparent width of the moon) on
Sept. 11. If you can locate Venus with binoculars in the twilight, Mars will
be situated just below and to the left of Venus. Mars will appear only 1/174
as bright as dazzling Venus, so don't expect to see it right away.
The next evening,
Venus is in conjunction with Mercury, but they're more widely separated at
3.6 degrees; Mercury will appear below and to the left of Venus. At
magnitude +0.2, Mercury is much brighter than Mars, but still only 1/44 as
bright as Venus. And creeping in from the east is Spica, about 7 degrees to
the upper left of the three planets.
Come Sept. 18, Venus,
Mercury and Mars will form an equilateral triangle, whose sides are 4
degrees in length. And Spica now becomes a part of this array, sitting only
a few degrees to the left of the triangle. Whether you'll actually be able
to see it, or the even fainter Mars against the backdrop of the bright
twilight sky, however, is debatable.
But to have three
planets and a bright star crammed into a relatively small spot in the sky
does not happen very often, so I would urge you to give it a try.
Drilling Into Alien Oceans
By
Lee Pullen
-
Astrobiology Magazine
 Some
of the most interesting places in our solar system are also the most
difficult to reach.
Areas hidden under
thick layers of ice such as the polar caps of Mars,
Saturn's moon Enceladus and Jupiter's moon
Europa are prime examples. Drilling through ice on
Earth is complicated enough, but on another world the task becomes almost
impossible.
The notion of exploring thick sheets of ice
isn't new. Probes built and used in the 1960s were strictly Earth-bound,
tested in places like Greenland and Antarctica, and the theory behind them
was fairly simple.
A long and thin probe penetrates straight
down into the ice. A drill on the tip cuts through the ice, scientific
equipment in the main body records data and a long cable trails out behind,
all the way up to surface equipment. Heavy and complex equipment is needed
on the surface to provide the vast amount of power needed by the large
drill, which rules it out for all but the most ambitious missions to other
worlds.
A different and more modern method of
drilling uses a hot drill tip to melt ice, rather than cut through it.
One such probe, called
Cryobot, was recently tested in Antarctica.
As the drill tip uses heat to melt ice, the probe sinks deeper and deeper.
Melting sounds good in theory, but if the probe hits something embedded deep
in the ice, like a large rock, it will get stuck. Unable to melt through,
the mission would come to an end.
The best of both worlds
Peter Weiss is a scientist experienced in
the field of sub-sea robotics. Together with his colleagues from the Hong
Kong Polytechnic University and the Institut fuer Weltraumforschung in Graz,
Austria, he has devised a novel way of combining drilling and melting
methods. The prototype "thermal drill" system they put together excelled in
tests, as detailed in the July 2008 issue of the journal Planetary and
Space Science. Armed with a series of blades and heaters in the tip, the
thermal drill could be the answer to exploring below the ice on distant
worlds.
But how does it work? Weiss explains, "Our
thermal drill is like a 'classical' melting probe, equipped with two
propellers that drill into the ice. We mechanically open up the hole in the
ice, and by this move the ice particles backwards where they will be melted.
The slurry of water and ice will be pushed backwards by the weight of the
probe."
Weiss's thermal drill
combines the best of drilling and melting techniques. "One advantage of
melting is that you can produce heat directly to melt through the ice, so
there are no losses due to the translation into mechanical power," he says.
As for the drill encountering layers of dust or other material that cannot
be melted through, Weiss says that "Integrating a drilling mechanism will
avoid your melting probe from simply getting stuck into a
layer of sand while penetrating the ice - a
scenario likely on the planet Mars, for example. A hybrid thermal drill will
be able to penetrate even layers that cannot be melted."
The heat created also has the useful
side-effect of sterilizing the probe, an essential consideration when
exploring places where no one has been before. The environment should be
kept pristine because contamination from the probe itself could ruin any
experiments to such for certain chemistry or even signs of life. The
constant production of heat also keeps the scientific equipment warm enough
in very cold environments to work effectively.
Destined for the solar system?
Many areas of our solar system are ideal
candidates for thermal drill exploration.
Says Weiss, "This
study was done targeting the planet Mars and Jupiter's moon Europa. But
since then spectacular new knowledge has been gained on worlds like
Enceladus or even Titan where scientists speculate about
sub-surface oceans."
Weiss and his colleagues have so far tested
their prototype thermal drill using large blocks of ice in a lab. Testing
the drill under vacuum conditions to simulate alien environments is a
logical next step. They'll also want to test just how deep the probe could
delve.
Despite high hopes for
the thermal drill, Weiss isn't sure whether one will feature on any upcoming
probes. He says, "ESA and NASA were discussing a future mission to icy
Europa, but it is uncertain if there will be a landing or impacting probe
onboard. But sending an orbiter without lander to Europa would be like going
to a candy shop without bringing money to spend."
NASA
Envisions Huge Lunar Telescope
By Jeremy Hsu
-
Staff
Writer/Space.com
 Telescope
mirrors made from lunar dust could help realize dreams of stargazing from
the far side of the moon.
Creating gigantic lunar
telescopes would normally carry an astronomical price tag, but NASA
researchers used a mix of epoxy, simulated lunar dust and carbon nanotubes
to demonstrate how to use materials already found on the moon.
"You can go to the moon with a
few buckets, and build something far larger than anything a rocket can
carry," said Peter Chen, a physicist at the NASA Goddard Space Flight Center
in Greenbelt, Md.
Orbiting vs. moon-based
Astronomers have argued about which is better in the
future: building additional orbiting space telescopes such as Hubble or
setting them up on the moon. Both
types of telescopes would be beyond the
interference of Earth's atmosphere, although the moon has the added
advantages of being a stable platform with a far side shielded from Earth's
cluttered radio background. On the other hand, getting to the moon
represents more of a challenge than simply launching a space telescope.
Astronauts
erect a telescope on the Moon, an artist's concept. Credit: NASA
However, the debate so far has
been "limited by launching from the ground," Chen told SPACE.com,
because Earth's gravity places both size and cost limits on what rockets can
carry into space or to the moon.
The solution: Get much of the needed building material
from the moon itself. Chen had already started working with epoxy and carbon
nanotubes to create "smart" materials that can flex or change shape when an
electric current passes through, but ended up adding
simulated lunar dust called JSC-1A Coarse Lunar
Regolith Simulant to the mix.
Chen used the resulting
lunar concrete as the foundation of a foot-long
disk, and poured more plastic epoxy on top of it. Then he spun the mirror at
a constant speed that formed the epoxy into a parabolic, slightly bowl-like
shape as it hardened. The mirror's finishing touch came with a thin layer of
reflective aluminum applied inside a vacuum chamber.
Making a Hubble-sized mirror
would require bringing 130 pounds (60 kg) of epoxy to the moon with 3 pounds
(1.3 kg) of carbon nanotubes and less than 1 gram of aluminum, according to
Chen's calculations. Meanwhile, 1,300 pounds (600 kilograms) of lunar dust
could provide the bulk of the material. The moon's lack of atmosphere also
suits the vacuum conditions needed to make the mirror.
Base considerations
Astronomers may imagine telescope mirrors half the
size of a football field, but realizing such dreams depends heavily on
whenever NASA
returns human explorers to the moon and sets up a
moon base.
Other challenges include
getting the necessary manufacturing equipment to the moon, such as the
spinning table on which the mirror gets created. Future astronauts would
also have to ensure that none of the free-floating lunar dust contaminates
the mirror.
"It's a great idea in
principle, but nothing is simple on the Moon," said James Spann, physicist
heading the Space and Exploration Research Office at Marshall Space Flight
Center, in a NASA statement.
Chen and his colleagues will
try to scale up their demonstration by creating 1.64-foot (0.5 meter) and
3.28-foot (1 meter) mirrors using the simulated lunar dust. They also plan
to figure out ways to hone the quality of the finished mirror's surface, and
are already speculating about ways future explorers and robots could build
even larger telescope mirrors on the moon — perhaps within an impact crater.
"It's totally out-of-the-box, but it's fun to
think about," Chen said.
For more information on Sky Watch opportunities
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