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February
25, 2009: For the first time, a spacecraft from Earth
has captured hi-resolution images of a solar eclipse while
orbiting another world.
Japan's
Kaguya lunar orbiter accomplished the feat on Feb. 9, 2009,
when the Sun, Earth and Moon lined up in a nearly perfect
row. From Kaguya's point of view, Earth moved in front of
the Sun, producing an otherworldly "diamond-ring"
eclipse. Click on the snapshot to launch a movie of the event
recorded by Kaguya's onboard HDTV camera:
Click
to play the movie!
The
sequence begins in complete darkness. At first, Kaguya couldn't
see the eclipse because it was blocked by the lunar horizon:
diagram. Soon,
however, the viewing angle improves and a thin ring of light
appears. This is Earth's atmosphere backlit by the sun. (Inside
that ring, sleepy-headed Earthlings are experiencing the first
light of dawn.) Just as the arc is about to join ends to complete
the circle—bloom! A sliver of the Sun's disk emerges, bringing
the eclipse to a sudden, luminous end.
Kaguya
is the largest mission to the Moon since the Apollo program.
Launched in late 2007, the spacecraft consists of a mother
ship plus two smaller orbiters that work together to relay
data to Earth even from the Moon's farside. Kaguya bristles
with 13 scientific instruments powered by 3.5 kilowatts of
electricity, enough to light up good-sized home on Earth.
So far the spacecraft has laser-mapped the Moon's surface
in 3D, searched polar craters for signs of lunar ice, probed
the gravitational field of the farside of the Moon—and much
more.
The
eclipse images are a bonus. Strictly speaking, Kaguya's HDTV
cameras (there are two of them) are not part of the scientific
payload. They were included on the spacecraft as a means of
outreach—to share Kaguya's view with Japanese citizens. Near
real-time transmissions broadcast on Japanese public television
are reportedly very popular.
Kaguya's
cameras would have come in handy forty years ago.
 On
April 24, 1967, NASA's Surveyor 3 lunar lander witnessed an
Earth-eclipse of the Sun from a crater in Mare Cognitium.
Only a crude snapshot, right, chronicles the event.
Right:
An eclipse of the Sun photographed by NASA's Apollo-era lunar
lander, Surveyor 3. [more]
In
Nov. 1969, Apollo 12 astronauts saw their own diamond ring.
It was "a marvelous sight," said Alan Bean. He was
flying home from the Moon along with crewmates Pete Conrad
and Dick Gordon when their spaceship flew through Earth's
shadow. "Our home planet [eclipsed] our own star,"
he marveled. Bean's photo of the event (click
here) improved upon Surveyor 3's, but couldn't match Kaguya's
modern video.
Later
this year, NASA will up the ante with the launch of Lunar
Reconnaissance Orbiter (LRO). The probe carries its own suite
of advanced scientific instruments including a camera powerful
enough to capture the outlines of moonbuggies and other hardware
left behind on the lunar surface by Apollo astronauts. Not
even Hubble has been able to do that.
When
LRO reaches the Moon, it will join Japan's Kaguya, China's
Chang'e-1 and India's Chandrayaan-1 missions already in orbit.
Never before has such an international fleet assembled for
lunar research. With so many spacecraft on duty, it is only
a matter of time before Kaguya's eclipse is itself eclipsed
by something even more marvelous. Stay tuned.
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Author: Dr.
Tony Phillips | Credit: Science@NASA
| more
information |
| Kaguya
-- (JAXA) mission home page
JAXA
press release (in Japanese)
JAXA
press release (in English)
Lunar
Reconnaissance Orbiter -- (NASA) home page
Who's
Orbiting the Moon? -- (Science@NASA) an international
fleet is assembling for lunar research
Abandoned
Spaceships -- (Science@NASA) For the first time
since the 1970s, a NASA spacecraft will get clear pictures
of Apollo relics on the Moon.
Diamond
rings: The term "diamond ring" has
a specific meaning among eclipse chasers on Earth. Diamond
rings or beads occur when the topography of the body
in front of the Sun isn't perfect, and some sunlight
gets in the cracks--e.g., sunlight shining through gaps
in lunar mountains when the Moon passes in front of
the Sun: photo.
Kaguya's diamond ring is a little different. It is a
snapshot of the moment just after the Sun is fully eclipsed.
The Sun coming out from eclipse saturates the camera,
creating a diamond ring effect, but that is not the
same diamond ring effect we see when observing a solar
eclipse from Earth.
NASA's
Future: US
Space Exploration Policy |
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