By JoEllen McBride, PhD
Fireballs streaking across the sky. Falling or shooting stars catching your eye. Meteors have fascinated humans as long as we’ve kept records. Depending on the time of year, on a clear night, you can see anywhere from 2 to 16 meteors enter our atmosphere and burn up right before your eyes. If you really want a performance, you should look up during one of the many meteor showers that happen throughout the year. These shows can provide anywhere from 10 to 100 meteors an hour! But what exactly is burning up to create these cosmic showers?
To answer this question we need to go back in time to the formation of our solar system. Our galaxy is full of dust particles and gas. If these tiny particles get close enough they’ll be gravitationally attracted and forced to hang out together. The bigger a blob of gas and dust gets, the more gas and dust it can attract from its surroundings. As more and more particles start occupying the same space, they collide with each other causing the blob to heat up. At a high enough temperature the ball of now hot gas can fuse Hydrogen and other elements which sustains the burning orb. Our Sun formed just like this, about 5 billion years ago.
Any remaining gas and dust orbiting our newly created Sun coalesced into the eight planets and numerous dwarf planets and asteroids we know of today. Even though the major planets have done a pretty good job clearing out their orbits of large debris, many tiny particles and clumps of pristine dust remain and slowly orbit closer and closer to the Sun. If these 4.5 billion year old relics cross Earth’s path, our planet smashes into them and they burn up in our atmosphere. These account for many of the meteors that whiz through our atmosphere unexpectedly.
The predictable meteor showers, on the other hand, are a product of the gravitational influence of the larger gas giant planets. These behemoths forced many of the smaller bodies that dared to cross them out into the furthest reaches of our solar system. Instead of being kicked out of the solar system completely, a few are still gravitationally bound to the Sun in orbits that take them from out beyond the Kuiper belt to the realm of the inner planets. As these periodic visitors approach our central star, their surfaces warm, melting ice that held together clumps of ancient dust. The closer the body gets to the Sun, the more ice melts– leaving behind a trail of particulates. We humans see the destruction of these icy balls as beautiful comets that grace our night skies periodically. But the trail of dust remains long after the comet heads back to edge of our solar system.
The dusty remains of our cometary visitors slowly orbit the Sun along the comet’s path. There are a few well-known dust lanes that our planet plows into annually. Some of these showers produce exciting downpours with over a hundred meteors an hour and others barely produce a drip. April begins the meteor shower season and the major events for 2017 are listed below.
|Moon Phase At Peak||Progenitor|
|Lyrid (N)||Apr 16-25||Aprl 22||12:00||Crescent||Thatcher 1861 I|
|Eta Aquarid (S)||Apr 19-May 28||May 6||2:00||Gibbous||1P/Halley|
|Delta Aquarid (S)||Jul 21-Aug 23||Jul 30||6:00||First Quarter||96P/Machholz|
|Perseid (N)||Jul 17-Aug 24||Aug 12/13||14:00/2:30||Third Quarter||109P/Swift-Tuttle|
|Orionid||Oct 2-Nov 7||Oct 21||6:00||First Quarter||1P/Halley|
|Taurids||Sep 7-Nov 19||
|Geminid||Dec 4-16||Dec 14||6:30||Crescent||3200 Phaethon*|
|Quadrantid (N)||Dec 26-Jan 10||Jan 3||14:00||Full||2003 EH1|
S= best viewed from Southern Hemisphere locations
N= best viewed from Northern Hemisphere locations
*This is an asteroid with a weird orbit that takes it very close to the Sun!
Here is a list of things you can do to ensure the best meteor viewing experience.
- Check the weather. If it’s going to be completely overcast your meteor shower is ruined.
- Is the Moon up? Is it more than a crescent? If the answer to both of these is yes you will have a more difficult time seeing meteors. The big, bright ones will still shine through but those are rare.
- When trying to catch a meteor shower, make sure the constellation the shower will radiate from is actually up that night. Hint: Meteor showers are named after the constellation they appear to radiate from.
- You need the darkest skies possible. So get away from cities and towns. The International Dark Sky Association has a dark sky place finder you can use. Your best bet is to find an empty field far from man-made light pollution.
- Make sure trees and buildings aren’t obscuring your view.
- It takes about 30 minutes for your eyes to completely adjust to the darkness. If you have a flashlight, cover it with red photography gel to help keep your eyes adjusted.
- Ditch the cell phone. Cell phones ruin your night vision. Every time you look at your screen your eyes have to readapt to the dark when you look back up at the sky. There are apps you can download that dim your screen (iPhone, Android) but your eyes will still need time to adjust to the darkness if you glance at your phone. Also looking away almost guarantees the biggest meteor will streak by at just that moment.
- Dress comfortably. In the fall and winter, wear warm clothes and have hot chocolate and coffee on hand. In the spring and summer, some cool beverages will enhance your experience. Make sure you have blankets to lay on or comfortable chairs so you can keep your eyes on the skies.
Follow these guidelines and you’ll have the best chance of watching 4.5 billion years of history burn up before your very eyes.
Paperfuges and Foldscopes: The Case for Low-Tech Science Next Post: