Solar minimum is here - but even now strangely beautiful auroras are dancing around the poles. Deep inside the Arctic Circle, the expert guides of Aurora Holidays in Utsjoki, Finland, can help you chase them. Book now! | | |
WILL ARCTIC SKIES TURN GREEN FOR CHRISTMAS? A minor stream of solar wind is approaching Earth. Estimated time of arrival: Dec. 24-25. No geomagnetic storms are expected, but the gaseous material could spark auroras around the Arctic Circle. Aurora Alerts: SMS Text.
THE FAINTING OF BETELGEUSE: One day, perhaps in our lifetimes, perhaps 100,000 years from now, the red giant Betelgeuse will dim a little--and then explode. The supernova will rival the full Moon in the night skies of Earth and cast shadows after dark. This month, Betelgeuse has dimmed a little. So far it has not exploded. Alan Dyer photographed the star rising as usual with the rest of Orion on Dec. 21st:
"This is Orion rising over my home in Alberta, Canada, on a partly cloudy and foggy night," says Dyer. "Yellow-red Betelgeuse is shining at upper left, reportedly dimmer than usual."
Betelgeuse caused a sensation among professional astronomers earlier this month when Edward Guinan of Villanova University and colleagues reported a significant "fainting" of the star. "[Betelgeuse] has been declining in brightness since October 2019, now reaching a modern all-time low of V = +1.12 mag on 07 December 2019 UT," they wrote. "Currently this is the faintest the star has been during our 25+ years of continuous monitoring."
Astronomers have long known that Betelgeuse is on the precipice of an energy crisis. It's about to run out of fuel in its core. When that happens, the star will collapse and rebound explosively, producing the first known supernova in the Milky Way since 1604. Experts in stellar evolution believe Betelgeuse could die at any time during the next 100,000 years--a blink of an eye on time scales of astronomy.
The current dimming did not herald that final blast. Betelgeuse is also a slow variable star, and this seems to be no more than an episode of slightly deeper-than-usual dimming. Orion remains in tact ... for now.
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CHRISTMAS GIFTS FROM THE EDGE OF SPACE: So far in 2019, the students of Earth to Sky Calculus have launched 41 space weather balloons to the stratosphere, measuring cosmic rays over 2 continents and 6 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 helium 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 "XMASRAYS" at checkout for a 10% holiday discount.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
ROCK COMET FIREBALL: So you thought the Geminid meteor shower was finished? Think again. On Dec. 21st, Frankie Lucena recorded an apparent Geminid fireball over Cabo Rojo, Puerto Rico:
"I traced this meteor back to the constellation Gemini near Castor, so I'm thinking it is quite possibly a late Geminid," says Lucena. "Also, the green afterglow is typical of bright Geminid meteors."
Geminids are bits of dust and gravel from 3200 Phaethon. The strange "rock comet" peppers Earth with debris every year in December. Of all the debris streams Earth passes through every year, 3200 Phaethon's is by far the most massive. Summed up, dust in the Geminid stream outweighs other streams by factors of 5 to 500.
No wonder, then, that Geminid stragglers are still hitting Earth's atmosphere more than a week after the shower's peak (Dec. 13-14). The debris zone of 3200 Phaethon is that big. In fact, it's so big that NASA's Parker Solar Probe has seen it without even trying. Stay tuned for more on that story in the days ahead.
Bonus: Also shown in Lucena's video is a tethered aerostat radar system. US Customs and Border Protection uses the moored helium balloon for low-level air and ground surveillance.
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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. 22, 2019, the network reported 6 fireballs.
(3 sporadics, 2 Leonis Minorids, 1 Ursid)
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 December 22, 2019 there were 2018 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2019 YR | 2019-Dec-17 | 8.7 LD | 11 | 27 |
2019 YB | 2019-Dec-18 | 0.4 LD | 12.8 | 4 |
2019 YY | 2019-Dec-18 | 17.1 LD | 8.1 | 24 |
2019 XF | 2019-Dec-18 | 9.3 LD | 24.1 | 79 |
2019 YS | 2019-Dec-18 | 0.2 LD | 7.2 | 2 |
2019 XO3 | 2019-Dec-18 | 3.3 LD | 9.5 | 21 |
2019 YH1 | 2019-Dec-18 | 2.7 LD | 9.8 | 22 |
2019 XQ3 | 2019-Dec-19 | 16.6 LD | 27.8 | 255 |
216258 | 2019-Dec-20 | 15.3 LD | 11.8 | 324 |
2019 YN | 2019-Dec-21 | 10.3 LD | 17 | 25 |
2019 YM | 2019-Dec-21 | 5.6 LD | 17.1 | 23 |
2019 YD1 | 2019-Dec-21 | 12.9 LD | 5.3 | 35 |
2013 XY20 | 2019-Dec-21 | 18.3 LD | 1.9 | 28 |
2019 YA1 | 2019-Dec-22 | 8.8 LD | 5.6 | 28 |
2017 XQ60 | 2019-Dec-22 | 10 LD | 15.6 | 47 |
2019 YR1 | 2019-Dec-22 | 12.3 LD | 16.5 | 25 |
2019 XP3 | 2019-Dec-23 | 18.3 LD | 8.9 | 42 |
2019 WB7 | 2019-Dec-23 | 2.8 LD | 6.9 | 43 |
2019 YO | 2019-Dec-24 | 15.5 LD | 3.6 | 18 |
2019 YE1 | 2019-Dec-24 | 13.6 LD | 6.2 | 32 |
2019 YU | 2019-Dec-24 | 19.5 LD | 16.4 | 85 |
2019 YB1 | 2019-Dec-25 | 4.2 LD | 5.6 | 17 |
310442 | 2019-Dec-26 | 19 LD | 12.3 | 372 |
2019 YQ | 2019-Dec-28 | 13.6 LD | 3.4 | 9 |
2019 YX | 2019-Dec-29 | 18.5 LD | 5.9 | 33 |
2019 WR4 | 2019-Dec-31 | 11.7 LD | 4.2 | 21 |
2019 YK | 2020-Jan-01 | 14.1 LD | 7.3 | 45 |
2019 AE3 | 2020-Jan-02 | 4.9 LD | 8.2 | 13 |
2019 YV | 2020-Jan-10 | 17.3 LD | 4.5 | 64 |
2019 UO | 2020-Jan-10 | 11.8 LD | 9.4 | 339 |
2019 WC5 | 2020-Jan-11 | 6.4 LD | 13 | 107 |
2011 EP51 | 2020-Jan-15 | 19.6 LD | 7.1 | 32 |
2017 RZ15 | 2020-Jan-15 | 12.1 LD | 7.4 | 14 |
2019 YG1 | 2020-Jan-17 | 17.5 LD | 4.4 | 30 |
2009 BH2 | 2020-Jan-18 | 14.6 LD | 17.9 | 118 |
2013 DU | 2020-Jan-20 | 14.9 LD | 6.4 | 59 |
2019 TF2 | 2020-Jan-23 | 16.2 LD | 1.6 | 18 |
2018 BM5 | 2020-Jan-23 | 13.1 LD | 8.6 | 12 |
2018 AL12 | 2020-Jan-30 | 18.2 LD | 17.7 | 39 |
2018 BU1 | 2020-Feb-02 | 19.4 LD | 10 | 41 |
163373 | 2020-Feb-15 | 15.1 LD | 15.2 | 589 |
2018 CW2 | 2020-Feb-17 | 6 LD | 10.2 | 28 |
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.
| The official U.S. government space weather bureau |
| The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| Realtime and archival images of the Sun from SOHO. |
| from the NOAA Space Environment Center |
| fun to read, but should be taken with a grain of salt! Forecasts looking ahead more than a few days are often wrong. |
| from the NOAA Space Environment Center |
| the underlying science of space weather |
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