Spotless Days Current Stretch: 0 days 2015 total: 0 days (0%) 2014 total: 1 day (<1%) 2013 total: 0 days (0%) 2012 total: 0 days (0%) 2011 total: 2 days (<1%) 2010 total: 51 days (14%) 2009 total: 260 days (71%) Updated 02 Dec 2015
Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2015 Dec 02 2200 UTC
Wednesday, Dec. 2, 2015
What's up in space
Marianne's Heaven On Earth Aurora Chaser Tours Chasethelighttours.co.uk invites you to join them in their quest to find and photograph the Aurora Borealis. Experience the winter wonderland in the Tromsø Area.
INTERPLANETARY SPACECRAFT TO BUZZ EARTH ON DEC. 3RD: Japan's Hayabasa 2 spacecraft, on a six year mission to catch and sample an asteroid, will fly past Earth on Dec. 3rd. Earth's gravity will slingshot the spacecraft toward its target, 162173 Ryugu, which Hayabasa 2 is expected to reach in July 2018. This animation from JAXA (the Japanese space agency) previews the flyby:
Many readers have never heard of Hayabasa 2. It is an amazing mission. After the spacecraft reaches Ryugu in 2018, it will orbit the asteroid for a year and a half. During that time, Hayabasa 2 will deploy four landers and drop a copper impactor to blow a hole in the asteroid's side. Hayabasa 2 itself will touch down on the asteroid, briefly, at least once to collect samples excavated by the impactor. In Dec. 2019, the spacecraft will leave the asteroid and use its ion engines to return to Earth, carrying precious samples of Ryugu. Ambitious? Yes. But if Hayabasa 2 completes even a fraction if its mission, it will be a success.
The spacecraft is small (mass: 590 kg, dimensions: 2 x 1.6 x 1.25 meters), so when it flies by Earth it will not be very bright--definitely invisible to the naked eye. "I expect it will be about 13th magnitude at best when it appears low in the west-northwest sky after evening twilight ends across the USA," says Richard Alan Keen of the University of Colorado, who observed a similar flyby of the Rosetta spacecraft in 2005, and bases his brightness estimate on that. Another experienced observer, Bill Gray of Project Pluto, estimates that the magnitude could reach +11. Either way, it is still very dim.
Observers with telescopes in Alaska, Hawaii and Japan are favored with the best views of the tiny spacecraft as it passes over the Pacific during closest approach. Ephemerides for specific locations may be obtained on the JPL HORIZONS website. Additional charts and a ground track are available in Japanese at this URL.
This just in: On Nov. 26th, at a distance of 3 million km, Hayabysa 2 took this picture of the Earth-Moon system:
According to JAXA analysts, you can see the Australian continent on the right, the Eurasian continent covered by clouds on the left, and the white vertical areas between them are clouds over the equator. Better views are expected as Hayabusa approaches Earth in the hours ahead.
SOUTHERN LIGHTS: It doen't feel like aurora season in New Zealand. "Summer is coming and it is getting warm," says southern photographer Taichi Nakamura. "Darker night hours are rapidly shrinking with only 5 hours at most between twilights." Nevertheless, during that narrow window of balmy darkness on Dec. 1, the auroras appeared:
"The subtle glow of Southern Lights appeared at midnight during super low tide at St. Clair beach in Dunedin," says Nakamura. "The iconic pier at the beach got washed away by Mother Nature a while ago. What remains still stands strong."
The display was caused by a solar wind stream, which hit Earth's magnetic field on Nov. 30th. The impact caused a G1-class geomagnetic storm and auroras around both poles. NOAA forecasters estimate a waning 25% chance of polar geomagnetic storms on Dec. 2nd as Earth slowly exits the solar wind stream. Aurora alerts: text or voice
Every night, a network of NASA 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 Dec. 2, 2015, the network reported 27 fireballs. (27 sporadics)
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]
Near Earth Asteroids
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 ones all the time.
On December 2, 2015 there were potentially hazardous asteroids.
These measurements are based on regular space weather balloon flights: learn more.
Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly "space weather balloons" to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. Here is the data from our latest flight, Oct. 22nd:
Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.
The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.