Image via Weekend a la Carte

UPDATED MAY 24, 2013 AT 1900 UTC (2 p.m. CDT). An M5-class solar flare on May 22, 2013 released a coronal mass ejection or CME. which has – as expected – now delivered a glancing blow to Earth’s magnetic field. The Advanced Composition Explorer (ACE) spacecraft – used by the Space Weather Prediction Center to provide warnings of these events – detected it beginning at about 1735 UTC (12:35 p.m. CDT) today. The Space Weather Prediction Center says to look for G1 (minor) geomagnetic storm levels over the next 24 hours. The estimate is for a 55% chance of polar geomagnetic storms in response to the strike. Aurora alert at high latitudes.

Full moon via Lance Bullion

What’s a supermoon? We confess: before a few years ago, we in astronomy had never heard that term. To the best of our knowledge, the term supermoon was coined by the astrologer Richard Nolle over 30 years ago. The term is only now coming into popular usage. Nolle has defined a supermoon as:

… a new or full moon which occurs with the moon at or near (within 90% of) its closest approach to Earth in a given orbit.

That’s a pretty generous definition and allows for many supermoons. The first “super” full moon – for 2013 – is tonight!

View larger. | Halo around the sun seen over New Jersey by EarthSky Facebook friend Jay Herbst. Thank you, Jay!

A ring or circle of light around the sun or moon is called a halo by scientists. We get many messages throughout each year from people who’ve just spotted a ring around the sun or moon. On May 14, 2013 a solar halo was seen over the U.S. east coast … see photos here. People want to know: what causes a halo around the sun or moon?

Photo credit: pizzodisevo

A solar eclipse happens at the new moon – when the moon passes between the sun and Earth. A lunar eclipse happens when the Earth, sun and moon align in space, with Earth in the middle. Why aren’t there eclipses at every full and new moon?

Image Credit: kevincole

Everyone around the globe can enjoy the Eta Aquarid meteor shower in early May. But it’s better viewed from the Southern Hemisphere than the Northern Hemisphere. Why? If you traced the paths of Eta Aquarid meteors backward on the sky’s dome, you’d find that these meteors appear to stream from an asterism, or recognizable pattern of stars, known as the Water Jar in the constellation Aquarius. The later sunrises in the Southern Hemisphere at this time of year let Aquarius rise higher into the predawn sky as seen from that part of the globe. More details inside this post.