Spotless Days Current Stretch: 0 days
2018 total: 165 days (57%)
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 15 Oct 2018
Current Auroral Oval:
Note to readers from Dr. Tony Phillips: "The current auroral oval is not updating properly. I have figured out the problem and am programming a solution. Normal updates should resume soon. Apologies for any inconvenience!"
Geomagnetic Storms: Probabilities for significant
disturbances in Earth's magnetic field are given for three activity levels: active, minor
Updated at: 2018 Oct 14 2200 UTC
Monday, Oct. 15, 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!
EARTH DODGES A METEOR STORM: On Oct. 8-9, European sky watchers were amazed when a flurry of faint meteors filled the sky at midnight. It was an outburst of the annual Draconids meteor shower. Turns out, that outburst was just the tip of the iceberg. Computer models show that Earth narrowly missed two streams of comet debris that would have caused significant meteor storms had they intersected our planet: full story.
GREEN RAIN FALLS ON NORWAY: On Oct. 13th, a crack opened in Earth's magnetic field. Solar wind poured in, fueling a G1-class geomagnetic storm and bright auroras around the Arctic Circle. Colin Palmer video-recorded the display from Tromso, Norway:
"It was a fine G1 outburst with coronas and curtains lasting well over 10 minutes," says Palmer.
In aurora-speak, a "corona" is what you see when auroras appear directly overhead, seeming to rain down in a luminous cascade that traces the rain of energetic particles from space. Palmer captured several fine examples. In the video, pay special attention to the sequence beginning at the 25 second mark.
The forecast calls for more green rain tonight. Earth is inside a stream of solar wind flowing from a ragged hole in the sun's atmosphere, and this will likely spark more Arctic auroras on Oct. 15th. Free:Aurora Alerts.
INFERIOR CONJUNCTION OF VENUS: On Oct. 26th, Venus will pass almost directly between Earth and the sun--an event astronomers call "inferior solar conjunction." As Venus approaches the sun, the planet is turning its night side toward Earth, reducing its luminous glow to a thin sliver. Astrophotographer Mariano Ribas of Buenos Aires, Argentina, took this picture on Oct. 14th:
"Venus looks really impressive in the eyepiece of my telescope--almost unreal," says Ribas. "The planet is looking bigger and thinner each day. I took the picture in broad daylight (4:30 pm local time) with my Meade LX90 12telescope and a Canon digital camera."
In the days ahead, the crescent of Venus will become increasingly thin and circular. The horns of the crescent might actually touch when the Venus-sun angle is least (~6 degrees) on Oct. 26th. This is arguably the most beautiful time to observe Venus--but also the most perilous. The glare of the nearby sun magnified by a telescope can damage the eyes of anyone looking through the eyepiece.
Anthony J. Cook of the Griffith Observatory has some advice for observers: "I have observed Venus at conjunction, but only from within the shadow of a building, or by adding a mask to the front end of the telescope to fully shadow the optics from direct sunlight. This is tricky with a refractor or a catadioptric, because the optics start at the front end of the tube. Here at Griffith Observatory, I rotate the telescope dome to make sure the lens of the telescope is shaded from direct sunlight, even through it means that the lens will be partially blocked when aimed at Venus. With our Newtonian telescope, I add a curved cardboard mask at the front end of the tube to shadow the primary mirror."
For the rest of this week Venus can still be observed without elaborate precautions in deep twilight after sunset. Every evening the crescent grows and narrows. Scan the realtime photo gallery for updates.
A JEDI IN THE STRATOSPHERE: "When 100,000 feet you reach, look as good you will not." –Yoda, 2018. Yoda has flown to the stratosphere. On Aug. 30, 2018, he hitched a ride on board an Earth to Sky Calculus helium balloon, traveling more than 101,362 feet above Earth's surface:
The students are selling these Jedi Christmas ornaments to support their cosmic ray ballooning program. You can have one for $97.95.
Each ornament comes with a unique gift card showing Yoda floating at the top of Earth's atmosphere. The interior of the card tells the story of the flight and confirms that the Jedi master has been to the edge of space and back again.
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 Oct. 14, 2018, the network reported 16 fireballs.
(14 sporadics, 1 epsilon Geminid, 1 chi Tauri)
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
ones all the time.
On October 15, 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.