Ever see ringlets of sunlight playing in
the shadows of a tree or a fiery ring of light in the sky? These incredible
effects are the results of an annular solar eclipse like the one that occurred
when the moon passed directly between the sun and Earth on Sunday, May 20,
2012. The event was viewable from Japan all the way across the Pacific Ocean to
midway through the United States.
Because the moon travels on a slightly
tilted orbit compared to the plane of Earth’s orbit around the sun, eclipses do
not occur every time the moon comes between the sun and Earth. However, there
are two points or "nodes" when the moon does pass through this plane.
If either of these nodes coincides with a new moon (when the sun is
illuminating only its far side), a solar eclipse will occur. If a node is
reached during a full moon, Earth will block the sun’s light, casting a shadow
onto the moon causing a lunar eclipse.
An annular eclipse occurs when the moon
is too far away from us to completely cover the disk of the sun. This results
in an annularity: the ring-shaped outline of the sun that can be seen
surrounding the dark new moon. Because of the surreal look of the "ring of
fire," annular eclipses are some of the most impressive celestial events
visible from Earth.
This eclipse passed over some of the
U.S.’s most famous national parks with the full annularity visible from 33
parks, while an additional 125 parks witnessed a partial eclipse. The NASA
Lunar Science Institute (NLSI) at NASA’s Ames Research Center, Moffett Field,
Calif., and the National Parks Service took advantage of this rare event and
joined forces to facilitate safe viewings for as many people as possible.
Several NLSI scientists traveled to the
Grand Canyon National Park and used the superimposition of our two most
prominent celestial objects as an opportunity to explain to several thousand
visitors about some of NASA's past, current and future projects relating to the
sun and moon. These include the Lunar Atmosphere and Dust Environment Explorer
(LADEE), which will orbit the moon in order to characterize its atmosphere and
the lunar dust environment, and the Interface Region Imaging Spectrograph,
(IRIS) which will make detailed measurements of the flow of energy and plasma
through the sun's atmosphere and heliosphere.
The NLSI team gave presentations to
three full-house audiences in the park’s theater and hosted an exhibit in its
main visitor center. Samples of moon and Mars rocks and meteorites that people
could handle were on display, as well as a model of a LADEE.
"Multiple missions to the moon in
the past five years have revealed our nearest celestial neighbor is a
fascinating place," said NLSI director Yvonne Pendleton, who spoke at the
event. "The Apollo-era views, rich in geological insights from samples
that continue to be studied today, have been enlarged to reveal detailed
topography, composition and a bombardment history that will fascinate
researchers for many years to come."
More than 2,000 people viewed the
eclipse at the event. Safe viewing equipment was also sent to other national
parks and another public viewing was held by one of the NLSI teams at the
University of Colorado football stadium in Boulder, where 10,000 people viewed
the partial eclipse.
"Nature has provided us with a
unique opportunity to capitalize on the huge public interest in the sun and
moon," said NLSI Director of Education and Public Outreach Brian Day.
"It is an excellent opportunity to engage with the public and explain what
we are doing at Ames."
Although there have been a number of
partial eclipses in recent years, May 20, 2012 was the first time in 18 years
that we have been able to see the moon pass directly across the center of the
sun from the U.S.
James
Schalkwyk
Ames
Research Center, Moffett Field, Calif.
Posts
No comments:
Post a Comment