Where's Saturn? Is that a UFO--or the ISS? What's the name of that
star? Get the answers from mySKY--a
fun new astronomy helper from Meade.
On Wednesday, July 25th at approximately 10:00 UT, "a major
daylight fireball tore across the skies of Slovenia, Croatia and
Italy," reports veteran meteor observer Jure
Atanackov of Maribor, Slovenia. "It produced two bright
flashes that reached an estimated magnitude of -20 and also loud
Magnitude -20? In plain language, the meteor was 600 times brighter
than a full Moon. Atanackov has gathered reports from hundreds of
eyewitnesses. "Most described the fireball as very bright,
its surface brightness almost as great as the Sun's. One person
said it was 'too bright to look at for more than a few moments.'"
This is not the fireball.
The image was posted by a Croatian
news service as an example of what the fireball looked like.
Non-speakers of Croatian misunderstood and widely circulated the
photo as a genuine record of the event.
The July 25th fireball falls into the category of superbolides--exploding
meteors of magnitude -17 or brighter. They are, essentially, small
asteroids measuring a few to 10 meters in diameter and massing a
few hundred metric tons. Superbolides trigger seismic detectors
on the ground, produce waves of infrasound that can travel thousands
of miles, and they are tracked by military satellites scanning Earth
for nuclear explosions. Recent examples include the El
Paso fireball of 1997 and the Yukon
fireball of 2000.
Eyewitnesses, please report your sightings to Jure
Atanackov or colleague Javor
Kac who are gathering data to learn more about the "Slovenian
Superbolide" and to estimate possible landing sites.
PROMINENCE ALERT: "What
a nice surprise," says Mark
Hanson of Middleton, Wisconsin. "This morning I was testing
a new focal reducer for my SolarMax90
when these nice prominences popped up."
They may look like flames, but prominences are something
different: gigantic clouds of hydrogen held together by solar magnetic
fields. Shortly after Hanson snapped the photo, above, Robert
La Porte, Indiana, caught the tallest prominence apparently breaking
This happens sometimes when a prominence's magnetic field becomes
unstable. Astronomers, now is the time to monitor
more images: from
N. Lowell, S. Hatfield and J. Stetson of South Portland, Maine;
P-M Hedén of Vallentuna, Sweden; from
Tom Masterson of Ferndale, Washington; from
Robert Arnold of Isle of Skye, Scotland; and a sketch from
Les Cowley of the UK.
Noctilucent Cloud Gallery