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VENUS-SATURN CONJUNCTION: When the sun goes down tonight, step outside and look southwest. Venus and Saturn are converging for a sunset conjunction. At closest approach on Dec. 11th, the two planets will be just under 2 degrees apart. Brilliant Venus pops out of the twilight first, followed ~15 minutes later by 1st-magnitude Saturn. Full story.
ONE WEEK FROM A SPACE AGE RECORD: 2019 is about to set a Space Age record. So far this year, the sun has been blank (no sunspots) for 262 days, including the last 25 days in a row. If the streak continues for only 7 more days, 2019 will break the Space Age record for spotless suns.
Above: The blank sun on Dec. 8, 2019. Credit: NASA/Solar Dynamics Observatory
The previous record-holder is the year 2008, when the sun was blank for 268 days, making the Solar Minimum of 2008-2009 the deepest of the Space Age. Next weekend, barring a sudden profusion of sunspots, 2019 will move into first place.
Solar Minimum is a normal part of the 11-year sunspot cycle. The past two (2008-2009 and 2018-2019) have been long and deep, making them "century-class" Minima. To find a year with more blank suns, you have to go back to 1913, which had 311 spotless days.
What are the side-effects of Solar Minimum? On one hand, solar flares and geomagnetic storms subside, making it harder to catch Northern Lights at mid-latitudes. Space weather grows "quiet." On the other hand, cosmic rays intensify. The sun's weakening magnetic field allows more particles from deep space into the solar system, boosting radiation levels in Earth's atmosphere. Indeed, this is happening right now with cosmic rays nearing a Space Age record.
Stay tuned for updates this week!
Realtime Spaceweather Photo Gallery
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THE NORTHERN LIGHTS PENDANT: On Dec. 6, 2019, the students of Earth to Sky Calculus launched a cosmic ray balloon to the stratosphere. This Northern Lights pendant went along for the ride, flying more than 107,612 feet above the rugged Sierra Nevada mountains of central California:
You can have it for $119.95. The students are selling these pendants to support their cosmic ray ballooning program. Each one comes with a greeting card showing the pendant in flight and telling the story of its journey to the edge of space. It makes an out-of-this-world Christmas gift!
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
IF YOU WANT TO SEE A CRAZY SUN HALO, GO SKIING... Many of us have seen a sun halo--a ring around the sun caused by ice crystals in clouds. The luminous rings are usually simple circles. On Dec. 1st, however, things got complicated. "I witnessed a very complex halo display," reports Cindy Bidois, who sends this picture from Val Thorens in the French Alps:
In Bidois's photo, we see a parhelic circle, a supralateral arc, a 22-degree halo, a circumzenithal arc, an upper tangent arc, a Parry arc, a sun pillar and a pair of sundogs. "It was crazy," she says.
Complex halos like this require not just one type of ice crystal, but many, with gem-like perfection and unusually precise crystal-to-crystal alignment. Clouds that contain such a rare ensemble of ice crystals are rare. In this case, the clouds had help--from snow-making machines.
Val Thorens, located at an altitude of 2300m, is the highest ski town in Europe. Snow-making machines at ski resorts produce a special type of ice. Crystals called "diamond dust" grow slowly downwind of ski-slope snow blowers. These man-made crystals tend to be more optically perfect than natural crystals in clouds, producing extra-bright, extra-sharp sun halos just like Bidois saw.
Realtime Aurora Photo Gallery
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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. 09, 2019, the network reported 6 fireballs.
(6 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]
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 9, 2019 there were 2018 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2019 XO2 | 2019-Dec-04 | 19.2 LD | 17.3 | 207 |
2019 XF2 | 2019-Dec-04 | 1.3 LD | 10.4 | 14 |
2019 XR1 | 2019-Dec-04 | 1.4 LD | 11.7 | 22 |
2019 XE2 | 2019-Dec-04 | 4.1 LD | 7.3 | 15 |
2019 WW | 2019-Dec-05 | 8.6 LD | 9.8 | 44 |
2019 XM2 | 2019-Dec-05 | 2.3 LD | 18.1 | 19 |
2019 WB5 | 2019-Dec-06 | 18.7 LD | 22 | 48 |
2019 XN | 2019-Dec-06 | 2.4 LD | 9.7 | 10 |
2019 WR3 | 2019-Dec-06 | 14.2 LD | 7.5 | 96 |
2019 WJ6 | 2019-Dec-07 | 7.5 LD | 21.1 | 48 |
2019 XT2 | 2019-Dec-07 | 1.4 LD | 8.4 | 18 |
2019 XP | 2019-Dec-07 | 5.5 LD | 12.2 | 17 |
2018 XW2 | 2019-Dec-07 | 17.4 LD | 13 | 28 |
2019 VH5 | 2019-Dec-08 | 18 LD | 9.8 | 76 |
2019 XY | 2019-Dec-09 | 3.2 LD | 13.1 | 9 |
2019 XB | 2019-Dec-09 | 17.3 LD | 7.9 | 69 |
2019 WT3 | 2019-Dec-09 | 9.8 LD | 11 | 40 |
2019 WO2 | 2019-Dec-09 | 4.8 LD | 7.6 | 32 |
2019 XW | 2019-Dec-10 | 10.8 LD | 15.6 | 59 |
2019 XO1 | 2019-Dec-13 | 7.9 LD | 7.9 | 44 |
2019 WP6 | 2019-Dec-14 | 6.4 LD | 4.4 | 22 |
2019 XF | 2019-Dec-18 | 9.4 LD | 24.1 | 77 |
216258 | 2019-Dec-20 | 15.3 LD | 11.8 | 324 |
2013 XY20 | 2019-Dec-21 | 18.3 LD | 1.9 | 28 |
2017 XQ60 | 2019-Dec-22 | 11 LD | 15.6 | 47 |
310442 | 2019-Dec-26 | 19 LD | 12.3 | 372 |
2019 WR4 | 2019-Dec-31 | 11.7 LD | 4.2 | 21 |
2019 AE3 | 2020-Jan-02 | 4.9 LD | 8.2 | 13 |
2019 UO | 2020-Jan-10 | 11.8 LD | 9.4 | 356 |
2019 WC5 | 2020-Jan-11 | 6.3 LD | 13 | 108 |
2011 EP51 | 2020-Jan-15 | 19.6 LD | 7.1 | 32 |
2017 RZ15 | 2020-Jan-15 | 12.1 LD | 7.4 | 14 |
2009 BH2 | 2020-Jan-18 | 14.6 LD | 17.9 | 118 |
2013 DU | 2020-Jan-20 | 15.3 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 |
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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