Comets, Meteors And Asteroids Flashcards Preview

Earth And Space > Comets, Meteors And Asteroids > Flashcards

Flashcards in Comets, Meteors And Asteroids Deck (13):

What is a comet?

Comets are cosmic snowballs of frozen gases, rock and dust roughly the size of a small town.


What happens when a comet’s orbit brings it too close to the sun? What does this form?

When a comet's orbit brings it close to the sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the sun for millions of kilometers.


How have comets helped make life on earth possible?

They may have brought water and organic compounds the building blocks eof life through collisions with Earth to the planet.


What are asteroids? Where are they located? What shape is their orbit? How many is there?

Asteroids are rocky, airless worlds that orbit our sun, but are too small to be called planets. Tens of thousands of these minor planets are gathered in the main asteroid belt, a vast doughnut-shaped ring between the orbits of Mars and Jupiter.


What are asteroids that come close to Earth labeled as?

Asteroids that pass close to Earth—and merit close watch—are called Near-Earth Objects, or NEOs.


Are all asteroids in the Asteroid Belt? What are the four largest asteroids in our asteroid belt?

No. Others orbit in near-Earth space and a few migrate or are thrown out to the outer solar system by gravitational interactions. The four largest asteroids in the belt are Ceres, Vesta, Pallas, and Hygiea.


How much mass do the four largest asteroids contain? What could you make if you combined all the material in the asteroid belt.

Half the mass of the entire belt while the rest of the mass is contained in countless smaller bodies. Planetary scientists estimate that if you could put all that material together that exists there today, it would make a tiny world smaller than Earth’s moon (the missing “Fifth” rocky planet.)


Where is the asteroid belt located? What is it’s distance from the sun? How wide is it? Are objects in the asteroid belt close together? Explain.

The Asteroid Belt is located in an area of space between the orbits of Mars and Jupiter.
That places it between 2.2 and 3.2 astronomical units (AU) from the Sun.
The belt is about 1 AU thick.
No. The average distance between objects in the Asteroid Belt is quite large. If you could stand on an asteroid and look around, the next one would be too far away to see very well.


What are meteors? What is the difference between meteoroids and meteors?

Shooting stars, or meteors, are bits of interplanetary material falling through Earth's atmosphere and heated to incandescence by friction. These objects are called meteoroids as they are hurtling through space, becoming meteors for the few seconds they streak across the sky and create glowing trails.


How often do meteors fall on Earth? How much/many? What is a dramatic increase in meteors falling called?

Scientists estimate that about 48.5 tons (44 tonnes or 44,000 kilograms) of meteoritic material falls on the Earth each day. Several meteors per hour can usually be seen on any given night. Sometimes the number increases dramatically—these events are termed meteor showers.


When do meteor showers occur? How are they named? Explain. Give examples. How is some dust from meteor showers captured?

Some occur annually or at regular intervals as the Earth passes through the trail of dusty debris left by a comet. Meteor showers are usually named after a star or constellation that is close to where the meteors appear in the sky. Perhaps the most famous are the Perseids, which peak around 12 August every year. Every Perseid meteor is a tiny piece of the comet Swift-Tuttle, which swings by the Sun every 135 years. Other meteor showers and their associated comets are the Leonids (Tempel-Tuttle), the Aquarids and Orionids (Halley), and the Taurids (Encke). Most comet dust in meteor showers burns up in the atmosphere before reaching the ground; some dust is captured by high-altitude aircraft and analyzed in NASA laboratories.


Do all meteoroids reach the ground? Where do these debris come from? What are meteoroids?

Most of the objects bombarding Earth vaporize in our atmosphere, but some of the larger pieces (from pebbles to boulder-sized rocks) actually fall to the ground. Most of the objects come from asteroids, which are objects made of various types of rock and have existed since the origin of the solar system. A small rocky or metallic chunk of material that travels through space is called a meteoroid. Very small meteoroids (the size of dust) are often referred to as micrometeoroids or space dust. These fragments may also be leftover comet debris, or were ejected in collisions between other solar system bodies such as the Moon or Mars.


Why do meteors glow? What is a meteorite? Where do most fall? What happens to the ones that land on land?

As a meteoroid travels through our atmosphere, it is heated by friction. That causes it to glow, and if this happens at night, we see a long streak of light known as a meteor.
If the object survives the trip and falls to Earth’s surface, it is known as a meteorite. Many of these fall into the ocean (since about 71% of Earth’s surface is covered by water). The rest fall on land, where they await discovery by meteorite hunters.