Space Weather Update: 12/07/2015
By Spaceweather.com, 12/07/2015
DAYTIME OCCULTATION OF VENUS: Set your alarm for dawn. On Monday, Dec. 7th, Venus and the crescent moon will have a beautiful close encounter in the eastern sky just before sunrise. The sight of Venus and the Moon in tight formation, framed by twilight blue, is a great way to start the day. [photo gallery]
For observers in North America, the show is not over at sunrise. The Moon is going to pass right in front of Venus in broad daylight. The occultation will look something like this:
Spaceweather.com reader Kerneels Mulder took these pictures on Sept. 11, 2010, when a similar occultation took place over South Africa.
The Dec. 7, 2015, occultation may be seen from almost all of North America:visibility map. On the west coast, Venus disappears behind the edge of the Moon around 8:00 a.m. Pacific Time (e.g., 7:53 a.m. in Seattle, 8:03 a.m. in Los Angeles). On the east coast, the event commences around 12:30 p.m. Eastern Time (e.g., 12:42 p.m. in Boston, 12:31 p.m. in Atlanta). Start watching at least a half hour early before Venus disappears. Venus is easy to see in broad daylight–if you know where to look–and on Dec. 7th the Moon will lead you right to it. More informationabout this event is available from Sky and Telescope
ROCKET SIGHTINGS: On Sunday afternoon, 4:45 pm EST, Orbital ATK’s Cygnus spacecraft launched from Cape Canaveral on a re-supply mission to the International Space Station. The ascending spacecraft and the booster stages of its Atlas V rocket were visible up and down the eastern seaboard of North America. In Halifax, Nova Scotia, Michael Boschat reports seeing “two fireball-like pieces moving parallel to each other, breaking up in the SSW at 5:57pm. The brighter one passing behind the trees was at least magnitude -12!”
“Both of the fireballs had fragments falling off the front,” he continues. “The brighter one was reddish in color; the dimmer one was blue. They took me by surprise.”
According to veteran satellite observer and orbits expert Ted Molczan, Boschat likely witnessed the re-entry of the 1st stage of the Atlas V rocket. “This map shows the NOTAM (Notice to Airmen) region where Stage 1 was intended to re-enter,” says Molczan. “Facing SSW, as reported, Boschat would have been looking toward the south end of the region.”
NASA says the Cygnus spacecraft itself is in orbit and heading toward the station. It is carrying more than 7,000 pounds of science experiments and supplies, including Christmas presents for the crew, equipment for spacewalks and air tanks for the station’s atmosphere. Browse the gallery for more sightings:
SOLAR WIND SPARKS AURORAS: Earth is inside a stream of solar wind flowing from a broad coronal hole on the sun. First contact with the stream on Dec. 5th sparked bright auroras around the Arctic Circle. Chad Blakley sends this picture from Abisko National Park in Sweden:
“Last night I spent most of the evening helping our guides prepare for their Nightly Aurora Photo Tours in Abisko National Park,” says Blakley. “After I finished helping the guides I could not resist the temptation to take my snowmobile out and play in the fresh layer of snow — and I am glad I did! The clouds parted overhead, allowing Abisko to show its true colors with a magnificent display of auroras.”
DAWN COMET HAS TWO TAILS: Now that the morning Moon is waning in brightness, amateur astronomers are once again getting a good view of Comet Catalina. Images reveal not one, but two tails. Akihiro Yamazaki sends this picture from Yamanashi, Japan, taken Dec. 4th:
“This is a 36 x 30 second exposure through my 6-inch Astro-Physics telescope,” says Yamazaki. “I used a SONY-A7S digital camera set at ISO 2500.”
Why does Comet Catalina have two tails? Almost all comets do. The sun-warmed nucleus of a comet spews a mixture of dust and gas into space. Quickly, the mixture separates into two distinct tails: The gaseous “ion tail” is pushed straight away from the sun by solar wind. The weightier dust tail resists solar wind pressure and aligns itself more or less with the comet’s orbit. In Yamazaki’s picture of Comet Catalina, the ion tail points up; the dust tail points down.
This is Comet Catalina’s first visit to the inner solar system–and its last. The comet’s close encounter with the sun in mid-November has placed it on a slingshot trajectory toward interstellar space. Although the comet is leaving the solar system, it will become easier to see in the weeks ahead as it approaches Earth. At the moment the comet shines like a 7th magnitude star–invisible to the naked eye. It could brighten by one or two magnitude by mid-January. Sky maps and observing tips may be found in this article from Sky and Telescope.
A date of special interest is Dec. 7th when the comet pairs up with the planet Venus and the waning crescent Moon in the early morning sky. Catalina will be about 4odegrees away from the Venus-Moon combo. Stay tuned for more information about that, and meanwhile browse the realtime comet gallery for sightings.
All Sky Fireball Network
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. 6, 2015, the network reported 28 fireballs.
(14 sporadics, 9 sigma Hydrids, 3 November omega Orionids, 2 Geminids)
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 December 7, 2015 there were 1637 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:Asteroid
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
Situation Report — Oct. 30, 2015Stratospheric Radiation (+37o N)
Cosmic ray levels are elevated(+6.1% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month.
Sept. 06: 4.14 uSv/hr (414 uRad/hr)
Sept. 12: 4.09 uSv/hr (409 uRad/hr)
Sept. 23: 4.12 uSv/hr (412 uRad/hr)
Sept. 25: 4.16 uSv/hr (416 uRad/hr)
Sept. 27: 4.13 uSv/hr (413 uRad/hr)
Oct. 11: 4.02 uSv/hr (402 uRad/hr)
Oct. 22: 4.11 uSv/hr (411 uRad/hr)
These measurements are based on regular space weather balloon flights: learn more.
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. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. Here is the data from our latest flight, Oct. 22nd:
Radiation levels peak at the entrance to the stratosphere in a broad region called the “Pfotzer Maximum.” This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 22th measurements, a plane flying at 45,000 feet is exposed to 2.79 uSv/hr. At that rate, a passenger would absorb about one dental X-ray’s worth of radiation in about 5 hours.
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.
speed: 691.0 km/sec
density: 2.8 protons/cm3
explanation | more data
Updated: Today at 1438 UTX-ray Solar Flares
6-hr max: B3 0904 UT Dec07
24-hr: C1 0421 UT Dec07
explanation | more data
Updated: Today at: 1400 UTDaily Sun: 07 Dec 15None of these sunspots has the type of unstable magnetic field that poses a threat for strong flares. Credit: SDO/HMI
Sunspot number: 38
What is the sunspot number?
Updated 07 Dec 2015
Current Stretch: 0 days
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 07 Dec 2015
Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/OvationPlanetary K-index
Now: Kp= 3 quiet
24-hr max: Kp= 4 unsettled
explanation | more data
Interplanetary Mag. Field
Btotal: 7.2 nT
Bz: 2.5 nT north
explanation | more data
Updated: Today at 1439 UTCoronal Holes: 07 Dec 15
Earth is inside a stream of solar wind flowing from the indicated coronal hole. Credit: SDO/AIA.Noctilucent Clouds The southern season for noctilucent clouds is about to begin. Monitor the daily daisies, below, from NASA’s AIM spacecraft for the first wisps of electric blue above Antarctica.
Switch view: Ross Ice Shelf, Antarctic Peninsula, East Antarctica, PolarUpdated at: 12-06-2015 17:55:02
Updated at: 2015 Dec 06 2200 UTC
Probabilities for significant disturbances in Earth’s magnetic field are given for three activity levels: active, minor storm, severe stormUpdated at: 2015 Dec 06 2200 UTCMid-latitudes