Meteor showers: 7 mesmerizing facts about one of the most stunning celestial events
- Every year, parts of the Earth experience events called meteor showers.
- These events are usually predictable, as they relate to Earth's movement through debris left by comets.
- The size of the meteors that make up the showers is usually very small, so there's nothing to worry about.
When you make a wish on a falling star, you're really giving your hopes and dreams to a tiny space rock that is burning up as it flies through the atmosphere of Earth. These magnificent streaks of light, sometimes known as meteors, have mesmerized people for millennia, especially when they come in flaming bursts during sky displays known as meteor showers.
Let's find out more about these incredible celestial events.
What is a meteor shower and how do they form?
A meteoroid is a space rock that could range in size from a dust grain to a small asteroid. Meteoroids that enter Earth’s atmosphere (or the atmosphere of another planet) and burn up to produce fireballs are called meteors.
What we see is a "shooting star." Although, that bright streak is not actually the rock, which is usually vaporized, but rather the glowing hot air around it as the hot rock zips through the atmosphere.
The size range of meteors is not set, but most are just millimeters in size. A meteoroid that survives its trip through the atmosphere and hits the ground is called a meteorite. Generally, less than 5 percent of the original object will make it down to the ground.
The glowing hot air that is being carried through the atmosphere, not the rock itself, is what is visible as that light streak. Although on most nights you can see several meteors an hour, sometimes this increases dramatically. This is referred to as a "meteor shower."
But why so many at one time?
Well, comets orbit the Sun in a similar manner to Earth and the other planets. The orbits of comets are typically very lopsided, in contrast to the relatively circular orbits of planets.
A comet releases a lot of dust and rock particles as a portion of its frozen surface melt off as the comet approaches the Sun. As the Sun's heat boils off more and more ice and debris, it spreads out throughout the comet's course, especially in the inner solar system (where we live). Then, when the Earth's orbit intersects that of the comet's debris trail, a meteor shower results as the Earth collides with the cometary debris.
While this sounds dramatic, it is not actually something to worry about.
Typically, meteoroids range in size from dust particles to small boulders. Large meteoroids rarely impact the surface because they largely burn up in our atmosphere.
However, there's a decent possibility you'll catch a stunning shooting star display in the middle of the night!
The bright streaks of a meteor shower can emerge anywhere in the sky, but their "tails" appear to return to the same region of the sky. The reason for this is that although every meteor is approaching us from the same direction, perspective causes them to appear to be farther apart as they move closer to Earth. It's similar to looking at two railroad tracks coming together from the middle of the tracks.
The constellation from which the meteors appear to originate is used to identify meteor showers. So, for instance, the annual Orionid Meteor Shower in October (which is linked to comet Halley) appears to have its origins close to the constellation Orion the Hunter.
Dust and particles perpetually bombard Earth from all directions. Additionally, astronomers can forecast estimates for how many meteors will strike Earth's atmosphere and from what direction during regularly scheduled "meteor showers."
Meteor showers can either be spectacular or a complete bust, depending on exactly where and when the path of particles lands in a particular year. A full moon's brightness can overpower a meteor shower's fainter meteors, while a new moon's gloomy sky is excellent for shooting star hunters.
The Moon can also have a big impact on a meteor shower's visibility.
Astronomers often refer to some larger meteors as "fireballs" or, if they explode in mid-flight, bolides. These can glow even brighter than Venus, are visible during the day, and can be heard up to 30 miles (48 km) away.
As they travel through the atmosphere, meteors can typically achieve speeds of up to 30,000 mph (48,280 kph) and temperatures of roughly 3,000 degrees Fahrenheit (1,648 degrees Celsius).
Most meteors disintegrate in the air because they are so small; some of them are smaller than a grain of sand. While very small particles of meteoroids commonly fall on Earth, larger ones that make it through the atmosphere and land on the surface of the Earth, however, are relatively uncommon.
That being said, scientists estimate that approximately 48.5 tons (44,000 kilograms) of meteoritic material arrives on Earth every day, according to NASA.
Depending on the object's composition, speed, and entry angle, it may or may not disintegrate. Greater stress is experienced by a quicker meteor traveling at an oblique angle (slanting as opposed to straight on). Iron meteors are more resilient to pressure than those composed of stone. Around 5 to 7 miles (8 to 11 km) above, where the atmosphere starts to get denser, even an iron meteor would typically fragment.
How are meteors (asteroids) formed?
As you've already come to appreciate, meteorites are simply whole, or bits of, asteroids that entire planet's atmosphere. We have already covered that process above, but what most people mean when they ask this question is how the bits of rock/material is generated in the first place.
In the same way that planets, asteroids, and comets orbit the Sun, so do chunks of rock or iron known as meteoroids. The Solar System is full of these meteoroids, especially the tiny objects known as micrometeoroids.
Along with the outer planets' gas giants and rocky inner planets, they orbit around the Sun. Even at the furthest points of the Solar System, in the Kuiper belt and Oort cloud, meteoroids can be found to exist.
Different meteoroids orbit the Sun in a variety of ways and at varying speeds. The solar system's fastest meteoroids move through it at a speed of about 42 km/s (26 miles/s). That is incredibly fast.
Many meteoroids are formed from the collision of asteroids, which orbit the Sun between the paths of Mars and Jupiter in a region called the asteroid belt.
When these asteroids collide, they leave behind crumbly pieces of debris called meteoroids. The power of the asteroid impact may force the asteroids themselves, as well as meteoroid debris, off of their normal orbits. The meteoroids may then be on a collision trajectory with the Moon or a planet.
Another way they can form is from comets that deposit meteoroids as they fly through space. The "dirty snowball" of the comet's nucleus releases gas and dust as it gets closer to the Sun. A huge amount of meteoroids and micrometeoroids could be present in the dusty tail. A meteoroid stream is a name given to the configuration in which meteoroids that a comet has dropped typically orbit.
Yet others are formed when rocks splinter off of the Moon and Mars after celestial bodies—often asteroids or other meteoroids—impact their surfaces. These kinds of meteoroids make up a very small portion of meteoroids.
Impacts from meteoroids are one of the main causes of "space weathering." The term "space weathering" refers to the processes that affect celestial bodies without an atmosphere, such as asteroids, moons, and some planets. Space weathering includes processes such as impacts with meteoroids and asteroids, which leave craters and eject more meteoroids and space dust into the solar system.
The majority of meteoroids are composed of heavier metals like nickel and iron as well as silicate minerals (those primarily composed of silicon and oxygen like quartz).
Scientists have divided meteorites into three main types: stony, iron, and stony-iron, and each of these has many sub-groups. Most of the meteorites found on Earth are stony. These are made up of minerals that contain silicates, although they also contain some metals, generally nickel and iron. There are two major types of stony meteorites: chondrites and achondrites, with chondrites making up the vast majority of meteorites found on Earth.
Stony-iron meteorites have nearly equal amounts of silicate minerals and metals, while iron meteorites are mostly made of iron and nickel. While stony meteoroids are smaller and more brittle, iron and nickel-iron meteoroids are larger and denser.
List of major meteor showers
There are believed to be somewhere around 900 suspected meteor showers, of which about 100 are confirmed, according to the Meteor Data Center. Of these, there are around six prominent meteor showers that are well worth trying to catch if you can.
1. Quadrantids tend to appear in December and January
Late December and early January are when this meteor shower generally happens. The raw material for this shower likely comes from 2003 EH1, which is either an asteroid or a potential "rock comet."
The shower's radiant (or apparent tail-end origin) tends to be in the constellation Bootes. During this event, around 80 meteors per hour fall with a velocity of 25.5 miles per hour (41 kilometers per second). Northern Hemisphere observers have the best views of the Quadrantids.
2. Lyrids appear at the tail end of April each year
Next up is the meteor shower called Lyrids. It is widely believed that this meteor shower originates from the Thatcher comet. Constellation Lyra is the Harp's "radiant."
During this shower, about 20 meteors fall per hour at a velocity of around 48 km/s/29.8 miles. If you want to see them, try looking for the star Vega. This is also one of the earliest meteor showers spotted by humans. Over 2.700 years have passed since it was first noticed.
3. Perseids can be seen in mid-August
Perseids appear in mid-August and are produced by comet 109P/Swift-Tuttle. Perseus is this meteor storm's radiant constellation.
During this shower, around 60 meteors fall per hour with a velocity of 36.6 miles per hour (59 kilometers per second). The Perseids are one of the most visible meteor showers. They are visible everywhere but are particularly visible in the Northern Hemisphere.
4. Orionids come and go in October and November each year
This meteor shower comes from the comet 1P/Halley. Its radiant is between the constellations of Orion and Gemini. The meteor shower produces around 15 to 70 meteors per hour, each traveling at a velocity of around 41 miles per second (66 kilometers per second). This makes the Orionid meteor shower one of the brightest and fastest; the meteors often leave glowing "trains" of debris that can last for several minutes.
The hours following midnight are the optimum times to watch this event, which is visible in both the Northern and Southern hemispheres.
5. Leonids can be viewed in mid-November every 33 years
Originating from the comet 55P/Tempel-Tuttle, the radiant for this shower is the constellation Leo. Meteors in this storm travel at a velocity of 44 miles per hour (77 kilometers per second), with somewhere around 15 meteors falling each hour. This ranks among the most brilliant, swift, and vibrant meteor showers of all.
A Leonid meteor storm, which peaks at hundreds to thousands of meteors per hour, occurs every 33 years or so. The last Leonid meteor storm occurred in 2002. The ideal time to watch the Leonids is around midnight local time. The term "meteor shower" originated with Leonid storms.
6. Geminids tend to be most active in the middle of December
Derived from 3200 Phaethon, a probable "rock comet" or asteroid, the Gemini constellation is this meteor shower's radiant. Meteors from this shower tend to travel at a velocity of around 22 miles per hour (35 kilometers per second), with about 120 meteors falling each hour.
Geminids are one of the best and most consistent yearly meteor showers. The meteors often have a yellow tint and the showers have been active since the middle of the 1800s. The best viewing times are at night and just before dawn, and they may be seen all throughout the world. Given that the showers are viewable from around nine or ten o'clock in the evening, the Geminids are regarded as one of the best prospects for youthful spectators with early bedtimes.
7. Other places in the Solar System get meteor showers too
Meteor showers can occur on the Moon as well. Meteor showers are also known to occur on Mars and its moons. This is supported by the existence of several impact craters. The density of the atmosphere on Mars is less than 1% that of the atmosphere at sea level on Earth.
The two worlds are more similar towards their top edges, where meteoroids collide. Because of the planet's distance from the Sun and slower velocity, meteor showers on Mars, if you could watch them, would be less brilliant than on Earth.
In general, it is challenging to view meteor showers on other planets, but meteor showers can occur on any celestial body with a fairly transparent atmosphere.
Facts about meteor showers
1. It is very unlikely you'll be hit by a meteor, but not impossible
Have you ever wondered how likely it is you could be hit, and possibly killed by a meteorite? Well, it is challenging to put a probability on the likelihood of getting hit by a space rock because the occurrences of these events are so few.
However, Stephen A. Nelson, a professor of Earth Sciences at Tulane University, released a study in 2014 that made the effort. He calculated that in 2007, the likelihood of dying from an impact with a meteorite, asteroid, or comet at between 1 in 75,000 and 1 in 250,000.
This may seem like long odds, especially when contrasted with the lifetime odds (in the U.S. as of 2020) of 1 in 101 for dying in a car accident, 1 in 1,450 for a fire, 1 in 35,074 for a catclysmic storm, 1 in 221 for a gun assault, 1 in 57,825 for a bee or wasp sting, 1 in 67 for an opiod overdose, or 1 in 11,688,054 million for winning the $1 million PowerBall lottery (as of 2022).
Nelson estimated a 1 in 75,000 chance of perishing in a major, worldwide asteroid or comet collision. When enormous things have hit the Earth in the geologic past, they have wiped out millions of organisms, even whole species. The majority of the organisms are killed by the aftereffects, which include heat, radiation, and dust that block out the Sun, rather than by the direct hit.
According to a similar calculation by astronomer Alan Harris, there is a 1 in 700,000 probability that a human will die from a space impact during their lifetime, with large-scale events carrying the majority of the risk.
2. The Perseids meteor shower was first recorded in ancient China
As previously mentioned, every year in August, the Earth crosses the orbital path of Comet Swift-Tuttle. Comets like this one constantly shed off debris as they fly around the Sun, and it is this debris along Swift-Tuttle’s path that causes the Perseids meteor shower.
Comet Swift-Tuttle takes about 133 years to orbit the Sun and has been shedding debris for thousands of years since it was first captured in its present orbit. In fact, the first record of the Perseids dates back to 36 AD in ancient Chinese annals.
The comet itself last approached Earth in 1992 and will next be visible from Earth in about 2125. When this happens, it will be a bright comet easily visible to the naked eye, but that will be for future generations to enjoy.
3. Meteor showers were once seen as augurs for the Gods' wishes
People have believed that meteors, comets, and even meteor showers are manifestations of the gods they worship, heralding either good or terrible fortune.
Both the Romans and the Greeks believed that these celestial objects served as a sort of omen of both good and terrible events. Some also thought that comets would herald the birth of a great person.
After Julius Caesar was assassinated in 44 BC, a comet is said to have appeared, and the populace saw this as a portent that he was about to be turned into a god. In 30 BC, the Roman writer Cassius Dio referred to meteor showers as "comet stars." After the death of Cleopatra, the Egyptian Queen, they are mentioned as omens.
The Perseid meteor shower is linked to the martyrdom of St. Lawrence (an early church deacon who passed away in 258 AD).
Some believed the meteor shower, which was at its peak at the time of the martyrdom, to be the tears of the saint.
4. Meteor shower tails come in different colors
Believe it or not, meteor shower tails come in a variety of colors. According to NASA, they can be either red, green, or yellow.
This is the result of the ionization of molecules in the meteor as it heats up during its trip through the atmosphere. These atoms' electrons change from one energy state to another, emitting a certain wavelength of light in the process.
Metal atoms in the meteoroid emit different colors of light as they are ionized: sodium (Na) atoms give off an orange-yellow light, iron (Fe) atoms a yellow light, magnesium (Mg) a blue-green light, ionized calcium (Ca+) atoms may give off a violet color, while a green color probably means that the meteor contains nickel.
Green is a common hue because iron-nickel meteors are the most frequent metallic meteors. When meteors strike the atmosphere quickly, this glow usually shines the brightest. For instance, swift Leonid meteors frequently emit a green hue.
In addition, the heating caused by the meteor's passage through the atmosphere may also lead to molecules of atmospheric nitrogen (N2) and oxygen atoms (O) giving off a red light.
5. The International Space Station has some protection from meteors
Since the International Space Station is fairly vulnerable to space debris and strikes from objects like meteors, it includes some shielding to help improve its chances of survival in space.
Called "Whipple Bumper Shields," this armor consists of layers of material that are separated by gaps. The idea is that when a layer is hit, it will absorb the momentum from the projectile, slowing it down, and, ideally, it will disintegrate, rendering it harmless by the time it reaches the next layer.
The crew is equipped with patch kits in case a projectile breaches the hull and enters the pressurized cabin.
To date, this armor has received various impacts, and none of them have penetrated the full extent of the shields. Hits have left marks on the solar panels, radiators, some handholds, and some trusses. A hit has occasionally been announced to the crew by a loud booming noise.
The ISS can also be alerted and relocated a few orbits before a potential impact if the item is in a low-earth orbit and is larger than about 10 cm. For more manageable objects, they take the chance.
6. The Earth is constantly bombarded with tiny meteors
According to NASA, the Earth is subject to tens of thousands of meteors over any given day. The vast majority of these, however, are tiny and usually only around the size of a piece of dust.
In fact, more than a kilogram of this dust, technically called interplanetary dust is said to fall to Earth every day. This dust is essentially made up from countless tiny meteors, asteroids, and comets that have passed by the Earth in the past.
7. Meteor tails can be used for radio signals
Organizations such as the National Weather Service can bounce radio signals off the ionized trails left by meteors.
This practice is often referred to as meteor scatter or burst communications. Data from automated weather stations and sporadic data from the relevant U.S. government agencies are collected using this process from time to time.
The majority of meteor scatter communications take place between radio stations that follow a specific schedule for broadcast and reception times. Similar techniques for gathering data in remote areas are used by many other nations and regions of the United States.
And that is your lot for today.
Meteor showers are fascinating celestial events to observe. Beautiful and awe-inspiring, they also give us clues about our planet's place in the wider universe around it.