Space Weather Information

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Diffuse, monoenergetic, and broadband aurora: The global precipitation budget

SPACE WEATHER BALLOON DATA: Almost once a week, and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with sensors that detect secondary cosmic rays, a form of radiation from space that can penetrate all the way down to Earth’s surface. Our monitoring program has been underway without interruption for 6 years, resulting in a unique dataset of in situ atmospheric measurements.


It was a busy night on October 11 for varied aurora phenomena, as the G2 aurora storm filled the sky with Northern Lights. This was from southern Alberta, where the display of curtains early in the evening showed horizontal “dune” structures, along with isolated blobs. Later, those blobs to the south were joined by a dim red SAR arc, invisible to the eye but the camera recorded it. A time-lapse shows it moving east to west.—Fish-Eye-Oct-11-201_1634065237.jpg

Latest results: Our most recent flight on June 25, 2021, confirms a trend of decreasing cosmic radiation:

Cosmic ray dose rates peaked in late 2019, and have been slowly declining ever since. This makes perfect sense. Solar Minimum was in late 2019. During Solar Minimum the sun’s magnetic field weakens, allowing more cosmic rays into the solar system. We expect dose rate to be highest at that time.

Now that Solar Minimum has passed, the sun is waking up again. Solar magnetic fields are strengthening, providing a stiffer barrier to cosmic rays trying to enter the solar system. The decline of cosmic radiation above California is a sign that new Solar Cycle 25 is gaining strength.

The Sunspot Number

Scientists track solar cycles by counting sunspots –– cool planet-sized areas on the Sun where intense magnetic loops poke through the star’s visible surface.

Counting sunspots is not as straightforward as it sounds. Suppose you looked at the Sun through a pair of (properly filtered) low power binoculars — you might be able to see two or three large spots. An observer peering through a high-powered telescope might see 10 or 20. A powerful space-based observatory could see even more — say, 50 to 100. Which is the correct sunspot number?

There are two official sunspot numbers in common use. The first, the daily “Boulder Sunspot Number,” is computed by the NOAA Space Environment Center using a formula devised by Rudolph Wolf in 1848:

R=k (10g+s),

where R is the sunspot number; g is the number of sunspot groups on the solar disk; s is the total number of individual spots in all the groups; and k is a variable scaling factor (usually <1) that accounts for observing conditions and the type of telescope (binoculars, space telescopes, etc.). Scientists combine data from lots of observatories — each with its own k factor — to arrive at a daily value.