Lyceum B - Astronomy - Week 38 - Meteoroids, Craters & Auroras

Aug 21, 2022
6 min read

Updated: Aug 23, 2022

Meteors, Meteorites, Shooting Stars are all basically the same thing.

These are all meteoroids - particles of matter from space that fall into our atmosphere at such high speeds that they burn as they fall.

These are thought to be fragments that have broken off asteroids. These fragments range in size and while a few of these fragments can be the size of a boulder or larger, most are the size of a grain of sand.

Like comets, meteoroids originate in the Asteroid Belt.

Some of these remain in a cluster that orbit the Sun. At times the orbit of Earth will travel into a stream of comet dust and we see a shower of meteors.

Here is a list of some of the more prominent meteor showers:

Delta Aquarius - maximum activity during July with maximum of 25 meteors an hour

Perseids - maximum activity during August with maximum of 50 meteors an hour

Orionids - maximum activity during October with maximum of 20 meteors an hour

Taurids - maximum activity during November with maximum of 10 meteors an hour

Leonids - maximum activity during November with maximum of 10 meteors an hour.

Germinids - maximum activity during December with maximum of 50 meteors an hour

Quadrantids - maximum activity during January with maximum of 50 meteors an hour

From spaceplane.nasa.gov:

An asteroid is a small rocky object that orbits the Sun. A meteor is what happens when a small piece of an asteroid or comet, called a meteoroid, burns up upon entering Earth’s atmosphere.

If a meteoroid comes close enough to Earth and enters Earth’s atmosphere, it vaporizes and turns into a meteor: a streak of light in the sky.

Because of their appearance, these streaks of light are sometimes called "shooting stars."

Because meteors leave streaks of light in the sky, they are sometimes confused with comets. However, these two things are very different.

https://www.lpi.usra.edu/science/kring/epo_web/meteorites/craters/ - meteorites and craters

When meteoroids enter our atmosphere, we call them meteors. Scientists estimate that several hundred million meteors enter our atmosphere every day. Most meteors were don’t see. The ones that burn so brightly, they light up to the point that we can see them, we call them fireballs or “shooting stars”. Most meteors burn up completely before they ever hit the ground, but if they do survive that descent and land on Earth, we call them meteorites. Usually by the time a meteor hits the ground, it is not traveling at a very high velocity and most of it has burned up along the way. But sometimes, a meteor is so big and the impact of it’s hitting the Earth is hard enough that it digs a crater in the Earth’s surface.

4:44 min - Arizona

https://www.youtube.com/watch?v=HCmTd_ajFm4

From National Geographic.org

https://education.nationalgeographic.org/resource/meteorite - video

Craters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. The high-speed impact of a large meteorite compresses, or forces downward, a wide area of rock. The pressure pulverizes the rock. Almost immediately after the strike, however, the pulverized rock rebounds. Enormous amounts of shattered material jet upward, while a wide, circular crater forms where the rock once lay. Most of the material falls around the rim of the newly formed crater.

The impact of a meteorite that would result in the creation of a Chicxulub-sized crater is something astronomers call an extinction-level event (ELE) or biotic crisis. Meteorites are just one possible cause of an ELE. ELEs have happened more than a dozen times in Earths history.

Many impact craters are found on the Earth’s surface, although they can be harder to detect. One of the best-known craters on Earth is Meteor Crater, near Winslow, Arizona. The crater was created instantly when a 50-meter (164-foot), 150,000-ton meteorite slammed into the desert about 50,000 years ago. Meteor Crater is 1.2 kilometers (0.75 miles) in diameter and 175 meters (575 feet) deep.

The Chicxulub Crater, on Mexico’s Yucatan Peninsula, was most likely created by a comet or asteroid that hit Earth about 65 million years ago. The crater is 180 kilometers (112 miles) wide and 900 meters (3,000 feet) deep. The object that created the Chicxulub Crater was probably about 10 kilometers (6 miles) wide.

The impact was so powerful the crater is called the Chicxulub Extinction Event Crater. Scientists say half the species on Earth—including the dinosaurs—went extinct as a result of the impact. The event was more than a billion times more explosive than all the atomic bombs ever detonated on Earth.

Extinction-level events actually have little effect on Earths biodiversity. Most life on Earth is microbial. Microbes, such as bacteria and algae, are not significantly affected by ELEs. It's only the larger life forms - trees, dinosaurs, people that face biotic crises.

Zodiacal Light

From wiki:

The zodiacal light (also called false dawn when seen before sunrise) is a faint, diffuse and roughly triangular white glow that is visible in the night sky and appears to extend from the Sun's direction and along the zodiac, straddling the ecliptic.

Sunlight scattered by interplanetary dust causes this phenomenon. Zodiacal light is best seen during twilight after sunset in spring and before sunrise in autumn, when the zodiac is at a steep angle to the horizon. However, the glow is so faint that moonlight and/ or light pollution outshine it, rendering it invisible.

The interplanetary dust in the Solar System collectively forms a thick, pancake-shaped cloud called the zodiacal cloud, which straddles the ecliptic plane.

Zodiacal light is produced by sunlight reflecting off dust particles in the Solar System known as cosmic dust.

Auroras

https://www.youtube.com/watch?v=sBWPCvdv8Bk

Auroras begin about 60 miles above the Earth's surface. They happen when the Sun gives out extra bursts of energy. These intense bursts of energy make the sky near the Poles glow as the colors slowly change colors.

From pbs.org:

https://www.pbs.org/wnet/nature/blog/aurora-fact-sheet/ - has a good video of an aurora

Aurora: a colorful light show in the sky caused by the interaction between Earth's magnetic field and charged particles from the Sun.

AKA: polar lights (aurora ploaris), northern lights (aurora borealis), or southern lights (aurora australis)

An aurora is a natural light display in the Earth's sky, predominantly seen in high-latitude regions. Auroras are the result of disturbances in the magnetosphere caused by solar wind.

The word "aurora" is derived from the name of the Roman goddess of the dawn, Aurora, who traveled from east to west announcing the coming of the sun.

From wiki:

An aurora (plural: auroras or aurorae), sometimes referred to as polar light (aurora polaris), northern lights (aurora borealis) or southern lights (aurora australis), is a natural light display in the Earth's sky, predominantly seen in high-latitude regions.

From mtu.edu:

What are the Northern Lights (Aurora Borealis)?

The northern lights surprise stargazers by appearing in many forms—from patches or scattered clouds, to streamers, arcs, rippling or dancing curtains. The lights move and change shape and color. Scientists attribute their vibrant colors to excited gases emitted in Earth's atmosphere; oxygen gives off the green color of the aurora.

What Causes The Northern Lights? Short answer? The sun.

A solar flare (energetic particles from the sun) floats through space on the solar wind, eventually penetrating the Earth's magnetic field. Electrons in the magnetic field sideswipe oxygen atoms or nitrogen molecules in the Earth's atmosphere. The bursts of colorful light—the northern lights—are colliding particles (usually electrons) and atoms; at collision, electrons can return to their initial, lower energy state, and in the process, release photons or light particles we know as aurorae.

Viewing the Northern Lights

It is notoriously hard to predict catching the northern lights—they are a naturally occurring phenomenon after all—and a clear night sky is a must. Maximize your changes of seeing an aurora borealis shower by following these tips no matter your location in the northern hemisphere.

Best Time of Year

Best bet to see those green and pink nightlights? August through April—October, November, and April being peak months. Check out NOAA's three-day forecast and 30-minute forecast (or download your favorite aurora app), hope for a clear night sky, and dress warmly before heading out.

There is no set time for the northern lights, as solar flare activity can even happen before dark. To increase your chances, watch forecasts after 10 p.m. When you head out, have some patience. The best light shows may be during the most unexpected times.

Best Time of Year

Best Viewing Locations

We can put this most simply: Find the darkest place you can. Activity starts in the north sky, and depending on strength, can spill overhead into the southern sky. Ideal spot? The south end of a lake or field, free of any man-made light.

https://www.youtube.com/watch?v=HJp5TKNwiFo

https://www.nasa.gov/feature/goddard/2016/nasa-s-themis-sees-auroras-move-to-the-rhythm-of-earth-s-magnetic-field

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