Autumn
is almost here, and it's a wonderful time for stargazing.
Find out what's up from Spaceweather
PHONE.
EQUAL
NIGHT:
On Saturday, Sept. 23rd, the sun crosses the celestial
equator, marking the autumnal equinox--the first day
of northern autumn. Equinox means equal night.
With the sun on the celestial equator, Earthlings will
experience 12 hours of daylight and 12 hours of darkness.
It's also the beginning of aurora
season!
ON
THE EDGE:
Today, astronomers are watching a beautiful hedgerow
prominence dance along the sun's limb. In England,
Les Cowley recorded the action using his solar
telecope plus pencil and paper:
.
"Sketching
solar prominences might be somewhat 19th-century, but
it does make you look hard," says Cowley. "Prominences
change before your very eyes, sometimes in just a few
seconds."
more
images: from
Pete Lawrence of Selsey, UK; from
Mila Zinkova of San Francisco, California.
EMERALD
SUNSET: "Tonight
I saw one of the most beautiful and long lasting green
flashes I've ever seen," says Mila
Zinkova of San Francisco, who took this picture on
Sept 17th:
The
green
flash, a brilliant glint of emerald almost on the
ocean horizon just as the sun disappears, relies on a
mirage to magnify small differences in refraction between
red and green light. This particular sunset "was
a very complex mock
mirage," says Zinkova. "It seemed that the
sun could not get enough of playing with [thermal air
layers over the Pacific Ocean] and produced a different
shape every moment."
Green
flashes, once thought to be a
myth, are certainly real. If you live on a western
coast, look for them at sunset.
SPACE WEATHER
SPACE WEATHER
