Coronal Mass Ejections Propelling Towards Earth
A CME propelled toward Earth by an M7
-class solar flare of April 18th is still en route to our planet. Forecast models predict an arrival on April 20th with a 75% chance of polar geomagnetic storms after it hits. The Solar and Heliospheric Observatory captured an image of the storm cloud billowigg away from the sun at ~1000 km/s (2.2 million mph).
NOAA forecasters expect the CME to trigger a G2
-class geomagnetic storm, which is to say "moderate." High-latitude power systems may experience voltage alarms. HF radio propagation could fade at higher latitudes, and auroras have been seen as low as New York and Idaho during such storms.
What Are The Lyrids?
The Lyrid shower officially kicked off April 16 and should continue through April 25, according to NASA
. Its peak typically lasts less than a day, and NASA says it will likely fall on Earth Day this year (Earth Night, actually). "This month's Lyrid meteor shower peaks on the night of April 22 and the morning of April 23," says Jane Houston Jones of NASA's Jet Propulsion Laboratory. "But you'll spot some Lyrids any night between the 16th and the 25th. The peak rate is expected to be 15 to 20 meteors per hour."
The Lyrids are named after the constellation Lyra, because that arrangement of stars -- including Vega -- marks the place in the sky where these meteors seem to originate, at least from our earthbound perspective. But Lyra is just a convenient reference point and namesake; Vega is 25 light-years away, for example, while meteors sizzle in our atmosphere only 60 miles above the surface.
The true source of the Lyrids is Comet Thatcher
, a long-period comet that last visited the inner solar system in 1861. Earth passes through its orbital path every April, crashing into a cloud of comet debris left behind more than 150 years ago. As that rubble strikes Earth's upper atmosphere at 110,000 miles per hour, it vaporizes into visible streaks of light. Thatcher, meanwhile, is far away in its 415-year orbit around the sun, and won't return to our neck of the woods until 2276.
A last-quarter moon may obscure some fainter Lyrids by brightening the night sky, but it shouldn't outshine the show completely. Viewers in the Northern Hemisphere can maximize their chances of seeing a Lyrid by fleeing urban areas, avoiding artificial lights and being patient. The odds also improve as Lyra moves higher in the sky, which is why the best viewing will occur between the final hours of Earth Day and the predawn hours of April 23. Only about 10 to 20 Lyrids are expected per hour, but the shower has been known on rare occasions to produce up to 100 per hour.
The Lyrids are relatively fast-moving meteors, unlike December's Geminids
, but they also tend to be bright. On top of that, about a quarter of them produce glowing trails of ionized gas known as "persistent trains
," assisting skywatchers by leaving an ephemeral trace of their path to oblivion.
For more about the Lyrids, check out the infographic below (click image for larger view), which was produced by the Giant Magellan Telescope Organization
to help promote the eponymous telescope it's building in Chile: