If you live under city skies inundated by scattered light, you may miss out on the fainter meteors.
Fortunately, the Bay Area has numerous places within a 20- to 30-minute drive that are partly sheltered from light pollution, if you’re willing to make the late-night trip. In the South Bay, Henry W. Coe State Park is a favorite dark-sky watching location. On the peninsula, there are numerous spots from the Santa Cruz Mountains northward along Skyline Boulevard for a pullover with partial protection from city light. In the East Bay, go for the Sunol area, Mount Diablo or a ridgeline pullout along the East Bay hills from Tilden Park southward into Hayward. In the North Bay, you can find miles of darkened rural skies from the coast eastward.
What is a meteor shower?
A meteor is a small piece of rock or metal, usually not much bigger than a pebble, that can be seen as it burns up in Earth’s atmosphere. Hitting the thin air 30 to 50 miles above Earth’s surface at speeds of tens of miles per second, each dust speck vaporizes to incandescence in a flash, leaving a glowing trail across the sky.
Long-exposure image of the sky during the 2012 Lyrids meteor shower. (NASA/MSFC/Danielle Moser)
A meteor shower happens when Earth passes through a trail of dust left behind in the wake of a comet. Comets are large chunks of rock, ice and other frozen materials, as well as a smattering of dust. A typical comet is several miles in diameter.
When a comet passes close to the sun, it is warmed and some of its ice sublimates into gas, blowing into space and carrying dust with it. Over time, the dust spreads out into a trail along the parent comet’s orbital path.
Where do the Lyrids come from?
Every year, as Earth orbits the sun, it passes through the dust trail of one comet or another, and we see a meteor shower.
The comet that left behind the dust for the Lyrids shower is called C/1861 G1 (Thatcher).
Diagram of a comet showing its icy nucleus, its ion and dust tails, and the trail of dust it leaves behind in its orbital path. (NASA)
No one alive today has seen Thatcher, which was discovered in 1861 by astronomer A.E. Thatcher when it last passed close to the sun. And no one alive now will ever see it. Thatcher takes over 415 years to orbit the sun, and won’t come close enough for us to witness until the year 2283!
So, as you lie on your blanket under the early morning sky, waiting for the next meteor flare to delight, think about how each one you see was left behind by a comet over 160 years ago.
Gone in a flash, but living on in our wonder.
