Posts by 

C. Alex Young


Sun activity: Minor geomagnetic storm last night

Sun activity for November 30, 2022. Sun activity from flaring has increased slightly. We report on yesterday's minor geomagnetic storm and auroral activity.

Aurora season: Why more auroras at equinoxes?

An aurora season occurs in October and March each year, due to the way the magnetic fields of the sun and the Earth work in conjunction with sun-Earth geometry.

Limb darkening is an optical effect on the sun

Limb darkening is an effect we can see on the sun where the edges of the sun are darker than the center, due to the amount of photosphere we're looking at.

Why are east and west on the sun reversed?

East and west on the sun are opposite from what you might expect. On the sun, east is to the left and west is to the right. Learn why here.

A Grand Solar Minimum? Or a normal sun?

A Grand Solar Minimum happens when the peaks of several solar cycles in a row show less than average intensity. Are we in one?

What does the sun’s X-ray flux tell us?

Solar physicists often speak of the sun's X-ray flux as being high, or low. Solar flares are like waves on the background ocean of the sun's X-ray flux.

Solar filaments, aka prominences, arc upwards

Solar filaments (aka prominences, when viewed on the limb of the sun) are large, bright arcs of solar material and magnetic fields.

A storm on the sun, and a great week for auroras

Aurora alert in effect for the next few days: the sun sent out a halo coronal mass ejection on November 2, 2021, due to arrive at Earth on November 4.

Solar storm and aurora starting October 30

A solar storm after an eruption on the sun is carrying plasma toward Earth, which should produce northern and southern lights this weekend.

Aurora alert! Pair of CMEs to jolt Earth’s magnetic field

Aurora alert! A pair of coronal mass ejections will reach Earth September 1-2, 2021. Though not dangerous to satellites or the grid, they might cause auroras.