When is the best time to see auroras? Where is the best place to go? And how do you photograph them? These questions and more are answered in a new book, Northern Lights - a Guide, by Pal Brekke & Fredrik Broms.
NASA SPACECRAFT HITS THE MOON: There's a new crater on the Moon. NASA's LADEE spacecraft, on a mission since Sept. 2013 to study the lunar atmosphere, has crashed. This event was deliberate. LADEE was near the end of its planned mission and the grazing impact gave researchers a chance to study "lunar air" very close to the Moon's surface: full story.
M7-CLASS SOLAR FLARE (UPDATED): Sunspot AR2036 erupted today, April 18th, at 1307 UT, producing a strong M7-class solar flare. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash:
An S1-class radiation storm is underway in the aftermath of the flare. However, this is a relatively minor storm which poses minimal threat to satellites and aircraft.
Of greater interest is a CME that emerged from the blast site. The Solar and Heliospheric Observatory recorded the storm cloud racing away from the sun at aproximately 800 km/s:
This CME could deliver a glancing blow to Earth's magnetic field on or about April 20th. Two or three minor CMEs are expected to preceed this on April 18th-19th, and the combined impacts could generate a geomagnetic storm during the weekend. High-latitude sky watchers should be alert for auroras. Solar flare alerts: text, voice
Space Weather Photo Gallery
THE TURQUOISE FRINGE: Lunar eclipses are supposed to be red, yet when the Moon passed through Earth's amber shadow on April 15th, many observers witnessed a softly-glowing band of turquoise blue. Robert and Elisabeth Slobins send this picture of the phenomenon from Fort Myers, Florida:
The source of the turquoise is ozone. Prof. Richard Keen, an atmospheric scientist from the University of Colorado explains: "During a lunar eclipse, most of the light illuminating the Moon passes through the stratosphere, and is reddened by scattering. However, light passing through the upper stratosphere penetrates the ozone layer, which absorbs red light and actually makes the passing light ray bluer!" This can be seen, he says, as a turquoise fringe around the red.
For years, Keen has been using lunar eclipses to probe the transparency of the stratosphere. When the stratosphere is clogged with volcanic ash and other aerosols, lunar eclipses tend to be dark red. The bright orange color of the April 15th eclipse, along with the ready visibility of the turquoise fringe, suggests that the stratosphere is clear. This is a key finding for climate change models.
To see the effects of ozone on the eclipse, you have to be looking at just the right moment. Readers are invited to browse the gallery for more examples:
Eclipse Photo Gallery
Aurora Photo Gallery
Mars Photo Gallery
Comet Photo Gallery
Every night, a network
all-sky cameras scans the skies above the United
States for meteoritic fireballs. Automated software
maintained by NASA's Meteoroid Environment Office
calculates their orbits, velocity, penetration depth
in Earth's atmosphere and many other characteristics.
Daily results are presented here on Spaceweather.com.
On Apr. 17, 2014, the network reported 6 fireballs.
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Potentially Hazardous Asteroids (PHAs
are space rocks larger than approximately 100m that
can come closer to Earth than 0.05 AU. None of the
known PHAs is on a collision course with our planet,
although astronomers are finding new
all the time.
April 19, 2014 there were 1465
potentially hazardous asteroids.
Notes: LD means
"Lunar Distance." 1 LD = 384,401 km, the distance
between Earth and the Moon. 1 LD also equals 0.00256
AU. MAG is the visual magnitude of the asteroid on
the date of closest approach.
official U.S. government space weather bureau
first place to look for information about sundogs,
pillars, rainbows and related phenomena.
call it a "Hubble for the sun." SDO
is the most advanced solar observatory ever.
views of the sun from NASA's Solar and Terrestrial
and archival images of the Sun from SOHO.
the NOAA Space Environment Center
underlying science of space weather