Spotless Days Current Stretch: 0 days 2018 total: 204 days (59%) 2017 total: 104 days (28%) 2016 total: 32 days (9%) 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%) 2008 total: 268 days (73%) 2007 total: 152 days (42%) 2006 total: 70 days (19%) Updated 12 Dec 2018
Thermosphere Climate Index today: 3.44x1010W Cold Max: 49.4x1010 W Hot (10/1957) Min: 2.05x1010W Cold (02/2009) explanation | more data Updated 12 Dec 2018
Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2018 Dec 12 2200 UTC
Wednesday, Dec. 12, 2018
What's up in space
Lights Over Lapland has a brand-new website full of exciting adventures in Abisko National Park, Sweden! Take a look at our aurora activities and book your once-in-a-lifetime trip with us today!
CHINESE SPACECRAFT ORBITS THE MOON: China's Chang'e-4 spacecraft is now orbiting the Moon following a four and a half day journey from Earth. Chang'e-4 is on an unprecedented mission to land on the Moon's farside. First, though, mission scientists must adjust the spacecraft's orbit and test a communication link between Earth and the mission's relay satellite "Queqiao," according to the China National Space Administration. Stay tuned for updates.
METEORS FROM A ROCK COMET: The Geminid meteor shower is underway as Earth enters a stream of debris from rock comet 3200 Phaethon. Forecasters expect the shower to peak on Dec. 13th or 14th with as many as 100 meteors per hour. Exactly one year ago, during the peak of the 2017 Geminids, Wally Pacholka witnessed this fireball over the desert northeast of San Diego, CA:
"A brilliant Geminid fell over the Jeep Sculpture in Anza Borrego Springs," recalls Pacholka. "It was a beauty!"
More bright Geminids are in the offing. Perhaps because of its gravelly nature, the shower is rich in fireballs--that is, meteors brighter than the planet Venus. Indeed, last night NASA's network of all-sky meteor cameras captured 23 Geminid fireballs over the United States--numbers that will increase sharply in the nights ahead.
The best time to look is during the dark hours before dawn when the constellation Gemini is high in the sky. [sky map] [photo gallery]
CHRISTMAS GIFTS FROM THE EDGE OF SPACE: So far in 2018, the students of Earth to Sky Calculus have launched 42 space weather balloons to the stratosphere, measuring cosmic rays over 3 continents, 2 hemispheres, and 7 different US states. You can help them pay their helium bill by purchasing a Christmas gift from the edge of space:
Every item in the Earth to Sky Store has flown to the stratosphere alongside an array of cosmic ray sensors. Carried aloft by giant balloons, these unique gifts travel above 99.7% of Earth's atmosphere, experiencing space-like blasts of cosmic rays, extreme cold, and a wild ride parachuting back to Earth after the balloon explodes. Even Amazon doesn't carry items this far out!
Don't forget to enter coupon code "SPACESANTA" at checkout for a 10% holiday discount.
A GEMINID BUZZES COMET 46P/WIRTANEN: The radiant of the Geminid meteor shower is not very far from approaching Comet 46P/Wirtanen. Their respective constellations, Gemini and Taurus, are next door neighbors. That means comet photographers can expect to catch some Geminids in their exposures. Indeed, that's exactly what happened to Joe Lawton of Gerald, Missouri, on Dec. 9th. "As I was photographing 46P/Wirtanen, a Geminid meteor blazed across the sky and disintegrated next to the comet!"
"I combined a series of still images to create this video," he explains. "You can see smokey debris from the Geminid meteoroid twisting in the winds of the upper atmosphere and ultimately dissipating."
How often is this happening? (1) Todd Bush of Banner Elk, North Carolina, (2) Harlan Thomas of Powderface Trail, Alberta, and (3) Dr. Paolo Candy of the Cimini Astronomical Observatory in Italy have also caught Geminids streaking past the comet. Images:North Carolina, Alberta, Italy.
Experienced observers report that Comet 46P/Wirtanen is now about as bright as a 5th magnitude star. Stars of that magnitude are visible to the unaided eye, but unlike a star, which concentrates its luminosity in a point, the comet's brightness is spread out over an area twice as wide as a full Moon. This makes it difficult to see naked-eye, but an easy target for digital cameras on tripods. Photographers submitting to our Comet Photo Gallery are having success with 10-to-60 second exposures at ISOs between 1600 and 6400.
Readers, would you like to photograph the comet and the meteor shower at the same time? It can be done during the hours before midnight when Gemini and Taurus are hanging together in the southeastern sky. These sky maps are tailored to that purpose: Dec. 12, Dec. 13. Dec. 14.
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. 12, 2018, the network reported 58 fireballs. (26 sporadics, 23 Geminids, 7 sigma Hydrids, 2 December Monocerotids)
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 12, 2018 there were 1936 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.
Cosmic Rays in the Atmosphere
SOMETHING NEW! We have developed a new predictive model of aviation radiation. It's called E-RAD--short for Empirical RADiation model. We are constantly flying radiation sensors onboard airplanes over the US and and around the world, so far collecting more than 22,000 gps-tagged radiation measurements. Using this unique dataset, we can predict the dosage on any flight over the USA with an error no worse than 15%.
E-RAD lets us do something new: Every day we monitor approximately 1400 flights criss-crossing the 10 busiest routes in the continental USA. Typically, this includes more than 80,000 passengers per day. E-RAD calculates the radiation exposure for every single flight.
The Hot Flights Table is a daily summary of these calculations. It shows the 5 charter flights with the highest dose rates; the 5 commercial flights with the highest dose rates; 5 commercial flights with near-average dose rates; and the 5 commercial flights with the lowest dose rates. Passengers typically experience dose rates that are 20 to 70 times higher than natural radiation at sea level.
To measure radiation on airplanes, we use the same sensors we fly to the stratosphere onboard Earth to Sky Calculus cosmic ray balloons: neutron bubble chambers and X-ray/gamma-ray Geiger tubes sensitive to energies between 10 keV and 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
Column definitions: (1) The flight number; (2) The maximum dose rate during the flight, expressed in units of natural radiation at sea level; (3) The maximum altitude of the plane in feet above sea level; (4) Departure city; (5) Arrival city; (6) Duration of the flight.
SPACE WEATHER BALLOON DATA: 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. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of more than 18% since 2015:
The data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
En route to the stratosphere, our sensors also pass through aviation altitudes:
In this plot, dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x.
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.
Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.