What is a shooting star?
Last Updated: April 27, 2021
One of the most beautiful aspects of astronomy and stargazing is looking up to see shooting stars (also known as falling stars) streaking across the night skies — the wonder and delight in spotting these are unmatchable. However, these are streaks of light caused by a phenomenon that is not related to stars at all!
What causes shooting stars?
Our solar system’s main celestial bodies are, no doubt, the planets. Lesser seen objects are asteroids and comets — pieces of rock that exist in between the planets and orbit the Sun along with other entities of the solar system. At times, some of these rocks are flung in the direction of Earth and enter its atmosphere.
While the smaller ones burn high up in the atmosphere, the bigger, heavier ones have large iron cores that the atmosphere’s friction cannot vaporize. These land on the surface and give way to craters.
The third kind is the ones that amateur astronomers most look forward to. When these rocks enter the atmosphere, they leave bright streaks in their wake as they burn up in the sky.
While more than 25 million such micrometeoroids enter Earth’s atmosphere every single day, the most prominent ones occur when Earth’s orbit around the Sun intersects a comet’s orbit. These are predictable regions in space where “meteor showers” occur, the most frequent ones of which include more than 100 shooting stars in less than an hour!
Small meteors entering the atmosphere at high speed causes the streaks of light known as shooting stars.
What are they made of?
Since shooting stars are meteors, or space rocks that become visible when they are heated up by the Earth’s atmosphere, they are made of the same hydrogen and carbon elements.
Most meteoroids contain nickel and iron in their cores. Among iron, nickel, carbon, and other elements, the kind of classification that a particular meteorite falls under depends on which of the chemicals is dominant in the meteorite.
What color are shooting stars?
If you’ve watched shooting stars before, you might have noticed that different meteor showers have different colors as they zip through the atmosphere. The colors themselves are caused because these meteorites that usually hover in space, where it is very cold, suddenly experience the heat caused by friction as they enter the Earth’s atmosphere. The chemicals inside the meteors vaporize due to this heat, the energy which is then seen as a green light by those on Earth’s surface.
The varying colors represent different chemicals that are vaporizing, and the intensity of the colors tell us how much of each gas is present inside of the meteors. In addition to these gases, the speed and angle at which the meteors fall also influence the color and its intensity that we see.
The faster a meteor moves, the more rapidly the gases burn, which leads to more intense color. This happens because gases themselves have different thresholds below which they are unaffected, so an increase in a meteor’s speed will cause more heat, causing gases with higher thresholds to burn as well. Those that are slower give rise to red or orange colors while faster ones spark a bright blue color.
This bright meteoric fireball from the annual Geminid meteor shower has a green hue.
How often do shooting stars happen?
We learned that shooting stars primarily happen because Earth’s orbit takes it through chunks of debris that result in meteor showers. So there are two kinds of shooting star events that we can classify. One is predictable showers, like Leonids, Perseids etc, where we know and can plan to view these showers.
The second category is the undocumented rocks that enter Earth’s atmosphere outside of the dedicated meteor showers because every now and then a stray rock might be flung in Earth’s direction by the gas giants, or attracted by Earth’s gravity. Either way, a handful of shooting stars every night (every 10 to 15 minutes) is perfectly normal.
Can a shooting star hit the Earth surface?
It absolutely can. Meteors start burning the moment they enter the Earth’s atmosphere, and many of them burn up completely many miles above its surface. But iron, which is at the core of meteors, takes time and more heat to burn. Larger meteors have higher iron content, which is why they are more likely to hit Earth’s surface, almost 500 of them each year.
How to observe a shooting star?
Since the major meteor showers occur in predictable points in Earth’s orbit, it is possible to plan observations for shooting stars.
- The first step, of course, is to go to a location that is dark enough for you to see the shooting stars. If you live in a city, you might want to consider traveling to its outskirts to avoid the city’s light pollution. Remember that even the darkest locations sometimes don’t allow the viewing of fainter shooting stars, but a dark enough location will allow you to observe the brighter ones enough to see their tails’ colors.
- The second step is to figure out which direction to look at. This depends on which meteor shower you are planning to observe. You will have to look at its “radiant point” accordingly. For example, the Perseids’ radiant point is the constellation Perseus, since that’s where the meteor shower originates.
- The third step is to plan your time as to when you can view the maximum number of shooting stars to make the most of your experience. For this, you’ll need to see when the “peak” of the shower occurs during the night. All meteor showers are best seen after sunset and before sunrise, so that gives you a starting point. The specific window will depend on how long a particular shower’s peak is. Perseids, for example, has a long peak across a week, so you can observe it any night around midnight.
Using a stargazing app will go a long way in helping you accomplish the above three steps and plan your shooting star party!
Meteor showers offer the best opportunities to see many shooting stars.
Falling star symbolism in different cultures
Shooting stars have occurred since Earth’s formation, and it is not surprising that they were fascinating yet bizarre experiences for past civilizations. Because they were trying to make sense of the night sky and its phenomenon, a variety of meanings arose in different cultures.
The famous Greek astronomer Ptolemy said that shooting stars are the gods that are trying to pry open the sky to see what’s happening on Earth. The people then started believing that an open sky would mean that gods are more likely to listen to their wishes and grant them. For this reason, it is also considered rude to point fingers at falling stars because the gods might get offended.
Another famous symbolism that is prevalent among many cultures, but not tied to a single one is that the stars represent falling souls, that after death the soul of the person has been released and they can go to heaven.
List of the major meteor showers
Meteor showers are the result of comet debris left in the path of the Earth. When the Earth travels on its trajectory around the Sun, it crosses the same debris fields again and again, which is why meteor showers happen at the same time each year.
|Name||Constellation||Number of meteors||Time of year|
|Lyrids||Lyra||20 meteors per hour||Mid to late April|
|Eta Aquarids||Aquarius||10 to 20 meteors per hour||Mid April to late May|
|Perseids||Perseus||120 meteors per hour||Mid July to mid August|
|Orionid||Orion||20 meteors per hour||October to November|
|Leonids||Leo||100 meteors per hour||October to end of November|
|Geminid||Gemini||50 meteors per hour||December|
Written by Tom Urbain
I’ve been fascinated by space and astronomy from a very young age. When I’m not watching space-themed documentaries, movies or TV series, I spend most of my free time in my backyard admiring the planets and galaxies with my telescope.
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