For daily wit & wisdom, sign up for the Almanac newsletter.
No content available.
When we gaze up at the night sky, it appears as a still-life scene. The one exception is when a streaking meteor suddenly pierces the sky. We’re talking about shooting stars. Would you believe a shooting star is just the size of a raisin? Learn all about these streaks of light—and how to see one!
The stars appear motionless. You’d have to leave and return ten minutes later to notice that the Moon and stars have shifted slightly to the right. (Our Aussie and Chilean friends see night sky objects move leftward in their Southern Hemisphere.)
But when we see a glowing light quickly shoot across the sky, everyone is startled and delighted. A shooting star, or a meteor, is the only rapid action in the nightly heavens.
A shooting star, or a meteor, is not a real star but a small piece of rock from space that enters Earth’s atmosphere. They’re also called fireballs.
Because this small rock is moving at such high speeds, the friction between the rock and air heats it up until the rock gets really hot and burns up in Earth’s atmosphere.
(By the way, a real star is a giant, hot, exploding ball of gas!)
What Causes a Shooting Star?
Since your average shooting star is only the size of a pebble or a raisin and visible at a typical height of 60 to 80 miles, it may seem fishy that a tiny glowing raisin could be seen at all. And your suspicions would be correct.
The meteor also heats up the surrounding air through which it travels, so it’s an incandescent air bubble a foot wide that’s streaking overhead. The speed is anywhere from 19 to 38 miles per second—say, somewhere in the vicinity of 100,000 miles an hour.
This friction melts part of the tiny rock or people, and it often evaporates, only leaving its streak of hot gasses across the night sky. That’s a shooting star!
Those normal, every-night shooting stars are called “sporadic.” (unlike meteor showers, which we’ll talk about later). You see many more of these shooting stars after midnight than before because that’s when your location on Earth has rotated to be on our planet’s forward-facing side as we zoom in our orbit at 18 miles a second.
What is a Meteorite?
If a space rock survives a trip through the atmosphere and hits the ground without dissolving into dust, which relatively few manage to do, it’s called a “meteorite.”
The little rock keeps being braked by friction. Encountering increasingly dense air below around 35 miles high, it gets too slow to be sufficiently heated to glow and vanishes from view.
Now, it simply falls unseen until it slams into the ground or a rooftop at only 300 miles an hour. That’s not fast enough to create a crater, but it is sufficient to penetrate a roof and maybe even one more ceiling of a house until it settles on the carpet of the ground floor.
About a dozen times a year, we’ll get what we call a “meteor shower”—which appears like a big burst of shooting stars during a short span of a couple hours or so. See an annual Meteor Showers Calendar.
When we get a full meteor shower, it’s not rocks that fall. Instead, they’re pieces of comets made of fragile icy chunks that cannot possibly survive their trip into our atmosphere. That’s why meteorites are generally pieces of asteroids, sturdy stuff, while no meteorite has ever come from a meteor shower.
Comets made of ice and dust. Or, call them “dirty snowballs,” a term coined by astronomy’s most renowned comet expert, Fred Whipple, with whom I conducted a weeklong cruise to show our guests comet Hale Bopp in 1996. Think of a comet as an overloaded pickup truck with icy chunks continually falling off. See my article to learn more about comets.
Over the centuries, streams of such comet debris may intersect Earth’s orbit so that we annually plow through them on the same date. The famous summer Perseid meteors all come from comet Swift-Tuttle, for example.
Then why call them Perseids? That’s because we name each meteor shower by using the possessive form of the background constellation from which they emanate. Just as railroad tracks seem to converge at a point in the distance, as do parallel power lines near the road, the meteoroids from a comet all move in parallel paths, so their “vanishing point” (to employ the term used by artists) is always in front of a particular constellation.
The Best Meteor Showers
The richest showers, defined as those that deliver around a meteor-a-minute, are the Perseids on August 11-12, the Geminids on December 13-14, and, irregularly every 33 years, the Leonids of November 17, which produced seven per minute in 2001. That was the last ultra-rich shower.
We pay attention to the Leonids because their swarms of meteoroids are sometimes incredibly thick. In 1833, the eastern United States witnessed 50 meteors per second over the course of a few hours. Many assumed it was a harbinger of major social changes, such as the abolition of slavery, and thus inspired the popular song “The Night the Stars Fell on Alabama.” When the Leonids failed to repeat that mind-numbing spectacle during the succeeding 33-year intervals, astronomers assumed some planet’s gravity had perturbed the swarm’s orbit, and the show had ended for keeps.
Thus, it was a big surprise when, on November 17-18th, 1966, the central U.S. again saw the sky continually filled with meteors, all emanating from a point in the constellation Leo as if a hole had been drilled through the heavens and giant sparks were now streaming in from another dimension. Some 60 per second were observed.
I later interviewed two eyewitnesses. One, Victoria Drowns, a young woman on a train in Texas who casually gazed out her window in the hours before dawn, saw the sky continuously filled with fast-streaking shooting stars and assumed it was Armageddon, the end of the world. What else could it be? She looked at the sleeping passengers in her compartment and hesitated. What’s the protocol, she recalls wondering? Do you wake strangers up for the end of the world or let them sleep through it? She called the conductor over, and together, they incredulously gazed at the spectacle until dawn erased it from the sky.
We probably won’t see such fireworks in our lives (though there’s a chance for it in 2099), so we’ll instead settle for the annual one-a-minute splendor of the Perseids and the Geminids. Since Earth’s orbit is virtually the same from year to year, the showers are predictable.
How to View a Shooting Star
You’ll see the most meteors on a clear, dark night without light pollution from city lights or moonshine.
Bright moonlight completely hides shooting stars. So, a reliable plan is to check the Moon’s phase ahead of time. The nearer to the new Moon, the better.
If one of the “big pair” of reliable yearly showers falls anytime between the last quarter and first quarter Moons—the half-month period surrounding the New Moon—plan to visit those friends in the country.
Then, the secret is simple but seldom followed. It’s polite to look at your companions when speaking to them. But on meteor night, under an open sky (not merely peeking through spaces between trees) and lounging on a reclining lawn chair to reduce neck strain, one must gaze steadily upward. Any direction is fine, and overhead is always good.
To see the most meteors, watch as late in the nighttime as you can, up till dawn. With the Perseids, the richest display runs from around 1 AM until dawn, while the much slower Geminids, which hit Earth sideways, are rich starting early, right at nightfall.
In all cases, don’t just glance up and then down to look at friends. Keep those eyes glued to the sky—the Perseids streak at a screaming 38 miles a second. Look down, and you’ll miss many of them. Most meteor showers are very fast! They flash by in a second or less.
A few times an hour, you’ll probably see a meteor bright enough to cast shadows, which is called a fireball. You may even see one explode into fragments, which is called a bolide. Along with the shower meteors that all come from one part of the sky (the northeast before midnight in the case of the Perseids), you’ll catch a few each hour that moves in totally different directions and display a divergent color or speed. Make a note – you’ve seen a sporadic!
Forget telescopes or binoculars. You want to view the largest possible patch of sky. This is a rare case where, in common with auroral displays, the more money spent on equipment, the less you’ll see.
For the haunting beauty of shooting stars, we may as well be back in the times of the ancient Greeks, who considered them strictly atmospheric phenomena, which is why the study of meteorology sounds—but is not—related to these welcome visitors from space.
Bob Berman, astronomer editor for The Old Farmer’s Almanac, covers everything under the Sun (and Moon)! Bob is the world’s most widely read astronomer and has written ten popular books. Read More from Bob Berman