High-latitude sky watchers should be alert for auroras this week when a
solar wind stream and a faint CME are expected to hit Earth's magnetic
field in quick succession. NOAA forecasters estimate a 45% to 65% chance of polar geomagnetic storms on April 21-22.
At the same time, Earth will be passing through a stream of debris from
Comet Thatcher, source of the annual Lyrid meteor shower. Sky watchers
are already seeing a smattering of late-night fireballs as Earth
approaches the diffuse core of the debris stream. Meteor rates are
expected to crest on April 22-23 with as many as 20 Lyrids per hour.