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! | | |
THE NEXT GEOMAGNETIC STORM: Minor G1-class geomagnetic storms are likely on Dec. 1st when a stream of solar wind hits Earth's magnetic field. The gaseous material is flowing from a large hole in the sun's atmosphere. This is a long-lasting hole that has lashed Earth with solar wind about once a month since July. The last time it happened on Nov. 4th, auroras were sighted in US states including Wyoming, Montana, Iowa, Washington, North Dakota and, of course, Alaska. It could happen again this weekend. Free: Aurora Alerts.
A HYPERACTIVE COMET IS APPROACHING EARTH: Small but hyperactive Comet 46P/Wirtanen is approaching Earth and could soon become visible to the naked eye. On Dec. 16th, the kilometer-wide ball of dirty ice will be less than 11.5 million km away--making it one of the 10 closest-approaching comets of the Space Age. It already looks magnificent through amateur telescopes. On Nov. 26th, Gerald Rhemann took this picture using a 12-inch reflector in Farm Tivoli, Namibia:
"The comet is currently gliding through the southern constellation Fornax," says Rhemann. "If you look carefully at the image, you can see galaxy NGC 922 near the comet's head, and another galaxy ESO 479-2 on the left."
Rhemann says that the comet's emerald green atmosphere is 50 arcminutes wide. In other words--almost twice as wide as a full Moon. Its apparent diameter could double in the weeks ahead as the comet comes even closer. Because Wirtanen's brightness is spread over such a wide area, it is diluted just below the limit of naked eye visibility, with a current magnitude near +6.0. We don't yet know if the comet will ultimately become visible to the unaided eye--but it will certainly be an easy target for binoculars and backyard telescopes in December.
The nucleus of 46P/Wirtanen is small (~1 km) compared to greater comets such as Hale-Bopp (~30 km) and Halley (~15 km). It makes up for this deficit by hyperactivity. Recent measurements show that the core of 46P/Wirtanen is spinning once every 8.9 hours and spewing almost 1028 water molecules every second. This exceeds the expected production of such a small comet.
Comet Wirtanen passes through the inner solar system every 5.4 years. Right now it is just below the orbit of Earth, and the gap is narrowing. Click on the image above to explore the comet's approach, courtesy of NASA/JPL.
More resources: sky map; ephemeris; 3D orbit; light curve.
Are you new to comet photography? Tutorials are available from award-winning astrophotographer Damian Peach.
Realtime Comet Photo Gallery
A GIFT FROM THE EDGE OF SPACE: Are you looking for a far-out gift? Nothing says "Merry Christmas" like a gem from the edge of space. The students of Earth to Sky Calculus flew this moonstone wrapped in a hand-crafted sterling silver Celtic love knot 35.1 km (115,158 feet) above Earth's surface:
You can have it for $179.95. The students are selling these pendants to support their cosmic ray ballooning program. Each one comes with a greeting card showing the item in flight and telling the story of its journey to the edge of space. All sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
INCREDIBLE SKI HALOS: Ski resorts are one of the best places to see sun halos--rings of light that surround the sun when ice crystals fill the air. Spaceweather.com reader Julie Morris was skiing at the Snowbasin Resort in Huntsville, Utah, on Nov. 25th when she witnessed this incredible specimen:
"I had never seen anything like it," says Morris. "It lasted for more than 15 minutes, and other skiers stopped to photograph it as well. I was so glad that my iPhone photo turned out because my hands were numb and I also couldn't see that well because I had stared at the brightness for so long!"
Ordinary sun halos are caused by ice crystals floating high above Earth's surface in cirrus clouds. "Ski halos," on the other hand, are formed by ice crystals near the ground, kicked into the air by the action of skis and snow-making machines.
"There were snow-making machines in operation at the time," says Morris. That's important because snow-making machines produce a very 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 halos.
Morris's quick iPhone photo captured a rare variety of forms: a 22-degree halo, sundogs, sub-sundogs, a sub-sun, a lower sun pillar, an upper tangent arc, a supralateral arc, a Parry arc, a 46-degree halo, a circumzenithal arc, and a parhelic circle--all sculpted from sunlight by floating diamond dust.
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
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 Nov. 28, 2018, the network reported 60 fireballs.
(59 sporadics, 1 November omega Orionid)
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 November 28, 2018 there were 1936 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2018 WD | 2018-Nov-24 | 4.5 LD | 13.6 | 49 |
2009 WB105 | 2018-Nov-25 | 15.2 LD | 18.9 | 71 |
2018 VT7 | 2018-Nov-25 | 8.2 LD | 2.3 | 10 |
2008 WD14 | 2018-Nov-28 | 9.5 LD | 9.4 | 93 |
2001 WO15 | 2018-Nov-28 | 13.6 LD | 11.7 | 107 |
2018 VE4 | 2018-Nov-30 | 15 LD | 4.8 | 30 |
2018 WN | 2018-Dec-01 | 14.9 LD | 4.4 | 17 |
2018 TG6 | 2018-Dec-02 | 3.9 LD | 1.4 | 13 |
2013 VX4 | 2018-Dec-09 | 4.1 LD | 6.6 | 65 |
2001 XG1 | 2018-Dec-10 | 7.9 LD | 14.2 | 78 |
2018 VX6 | 2018-Dec-10 | 16.5 LD | 11.2 | 70 |
2015 XX169 | 2018-Dec-13 | 17 LD | 5.8 | 12 |
2018 VO9 | 2018-Dec-15 | 2.6 LD | 2.9 | 15 |
2017 XQ60 | 2018-Dec-21 | 11.3 LD | 15.6 | 47 |
163899 | 2018-Dec-22 | 7.4 LD | 6.2 | 1232 |
418849 | 2018-Dec-23 | 16.6 LD | 17.6 | 269 |
2014 AD16 | 2019-Jan-04 | 12.9 LD | 9.4 | 12 |
2016 AZ8 | 2019-Jan-07 | 11.6 LD | 9.1 | 224 |
2013 YM2 | 2019-Jan-09 | 7.3 LD | 4.3 | 20 |
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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