Spotless Days Current Stretch: 1 day 2017 total: 82 days (25%) 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%) Updated 20 Nov 2017
Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2017 Nov 20 2200 UTC
Monday, Nov. 20, 2017
What's up in space
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CHANCE OF STORMS, TODAY AND TOMORROW: A stream of solar wind is approaching Earth. Estimated time of arrival: today. NOAA forecasters say there is a 40% chance of G1-class geomagnetic storms on Nov. 21st and 22nd as Earth moves through the gaseous material, which is flowing from a hole in the sun's atmosphere. Arctic sky watchers should be alert for auroras after local nightfall.Free:Aurora Alerts.
INTERSTELLAR ASTEROID "LIKE NOTHING SEEN BEFORE": In Oct. 2017, the Pan-STARRS 1 telescope in Hawai'i picked up a faint point of light moving across the sky. At first it appeared to be an ordinary asteroid--but astronomers quickly realized it was something entirely different. The hurtling object, since named "'Oumuamua," came from interstellar space. At the time of its discovery, 'Oumuamua had just swung around the sun. Telescopes around the world swiveled to observe it before it could leave the Solar System. Findings from those rapid observations were published in today's issue of Nature, and they reveal a very strange object indeed:
Above: an artist's concept of interstellar asteroid 'Oumuamua [more]
According to a European Southern Observatory (ESO) press release, 'Oumuamua is "like nothing seen before." It is red, made of dense rock or metal, and is shaped roughly like a giant cigar at least 400 meters long.
These are the findings of a team of astronomers led by Karen Meech (Institute for Astronomy, Hawai`i, USA) who combined images from the ESO's Very Large Telescope in Chile with other large telescopes. 'Oumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours. "This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape," says Meech.
The asteroid's dark red color is probably caused by cosmic rays irradiating its surface for millions of years in deep space. Cosmic rays have a similar coloring effect on asteroids and comets native to our outer Solar System.
Extrapolating 'Oumuamua's trajectory back in time, it seems to come from the direction of the star Vega. However, Vega itself moves and was not in the area when 'Oumuamua was last there ~300,000 years ago. 'Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System.
Researchers estimate that interstellar asteroids similar to 'Oumuamua pass through the inner Solar System about once per year, but they are faint and so have been missed until now.Only recently have survey telescopes such as Pan-STARRS become powerful enough to discover them.
"We are continuing to observe this unique object," says team member Olivier Hainaut from the ESO in Garching, Germany. "And now that we have found the first interstellar rock, we are getting ready for the next ones!" Stay tuned.
NEW ATMOSPHERIC RADIATION DATA: Last week's double launch of space weather balloons over Mexico and California was a success. The goal of our experiment was to measure cosmic rays in the atmosphere above both countries and compare the results. A first look at the data reveal big differences.
These curves show dose rate vs. altitude. They diverge rapidly above 15,000 feet, with radiation levels over central California typically 1.5 times higher than over Mexico. This means air travelers over California can expect to receive significantly greater doses of cosmic radiation compared to their counterparts flying south of the border. In both places, radiation levels reached a peak in the stratosphere. At those altitudes, dose rates were 60 times greater than sea level for Mexico, 90 times greater than sea level for California.
The reason for these differences is Earth's magnetic field which, generally speaking, provides greater shielding against cosmic rays near the equator (Mexico) than at mid-latitudes (California)
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. They trace secondary cosmic rays, the spray of debris created when primary cosmic rays from deep space hit the top of Earth's atmosphere.
Our payloads also carried neutron sensors. Stay tuned for updates next week as we continue our analysis of data from those detectors.
A CRYSTAL BALL IN THE STRATOSPHERE: For the first time ever, a crystal ball has visited the stratosphere. The students of Earth to Sky Calculus launched it on Oct. 19, 2017--a combination optics experiment and fundraiser. Watch the video as the crystal orb travels onboard a giant helium balloon 93,000 feet above Earth's surface, stretching, focusing, and inverting the incredible landscape of the Sierra Nevada mountains behind it:
This 800 gram crystal ball contains an embedded model of the Solar System, including the sun, eight planets and their moons. It makes an incredible gift for anyone interested in space.
We have flown only a small number of these heavyweight crystal balls. You can have one for $199. Each crystal ball comes with a unique gift card showing the item at the edge of space and telling the story of its flight. It also comes with a complementary crystal stand so you can display this unique keepsake on a desktop or shelf. QUANTITIES ARE LIMITED.
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. 20, 2017, the network reported 49 fireballs. (26 sporadics, 16 Leonids, 5 Northern Taurids, 1 Quadrantid, 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]
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 November 20, 2017 there were 1853 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
Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:
This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. 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. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.
What is this all about? 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 13% since 2015:
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 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.
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.