CHANCE OF STORMS: Today, Earth is expected to cross through a fold in in the heliospheric current sheet. At about the same time, a minor solar wind stream will hit our planet's magnetic field. The combined effect of these two events could be a polar geomagnetic storm; the odds are 35%, according to NOAA. Arctic sky watchers should be alert for auroras on Jan.12th and 13th. Free: Aurora Alerts
SUNSPOTS VANISH, SPACE WEATHER CONTINUES: So far in 2017, the big story in space weather is sunspots--or rather, the lack thereof. The sun has been blank more than 90% of the time. Only one very tiny spot observed for a few hours on Jan. 3rd interrupted a string of spotless days from New Years through Jan.11th. Devoid of dark cores, yesterday's sun is typical of the year so far:
The last time the sun produced a similar string of spotless days was May of 2010, almost 7 years ago. That was near the end of the previous deep Solar Minimum. The current stretch is a sign that Solar Minimum is coming again. Sunspot numbers rise and fall with an ~11-year period, slowly oscillating between Solar Max and Solar Min. In 2017, the pendulum is swinging toward the bottom.
Contrary to popular belief, space weather does not stop when sunspots vanish. Recent nights are proof: Bright auroras have been dancing around the Arctic Circle. Tom Arne Moldenaes of Norway,Groetfjord, recorded this eruption ("like green lava from a volcano," he says) on Jan. 5th when the face of the sun was completely spotless:
The auroras were sparked by a stream of solar wind flowing from a large hole in the sun's atmosphere. Such "coronal holes" are common during Solar Minimum.
Sunspots are an important source of space weather. They can unleash solar flares, cause radio blackouts and geomagnetic storms. However, equally interesting things happen when sunspots vanish. For instance, the extreme ultraviolet output of the sun plummets. This causes the upper atmosphere of Earth to cool and collapse. With less air "up there" to cause orbital decay, space junk accumulates around our planet.
Also during Solar Minimum, the heliosphere shrinks, bringing interstellar space closer to Earth. Galactic cosmic rays penetrate the inner solar system with relative ease. Indeed, a cosmic ray surge is already underway, with implications for astronauts and even ordinary air travelers.
Stay tuned for updates as we enter a new phase of the solar cycle.
URSUS STRATOSPHERUS: Valentine's Day is coming. To prepare, you might need a space bear. Or two:
To fund their cosmic ray research, the students of Earth to Sky Calculus have flown 20 pairs of brown bears to the edge of space. You can have a pair for only $69.95--including the rose, which has been pressed for safekeeping. Each adorable duo comes with Valentine's card showing the bears in flight and certifying their trip to the stratosphere.
More out of this world gifts may be found in the Earth to Sky store. All proceeds support cosmic ray balloon launches and STEM education.
Realtime Space Weather Photo Gallery
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. On Jan. 9th, Stefanie Nopper was riding the cable car to Switzerland's Melchsee-Frutt ski resort when she witnessed this specimen:
"First I saw a tiny rainbow and suddenly I realized, there is more than one... NO, it was an entire HALO!" she says. "I snapped this picture through the window using my iPhone."
Most 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.
Crystals emerging from snow-making machines can be particularly influential. A variety called "diamond dust" grows 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.
Going skiing? Be alert for halos. More examples may be found in the realtime photo gallery.
Realtime Space Weather Photo Gallery
Realtime Airglow Photo Gallery