Comets have 4 parts a nucleus, coma, plasma tail, and dust tail. The nucleus is the only permanent part of the comet although it has never been seen. The brightness of the comet can depend on how large the nucleus diameter is since comets can scatter reflect like a mirror.
Comets When a comets passes by the sun it goes from a solid to a liquid due to the intense heat. As it transforms it releases gas and dust which creates a transparent circle around it which makes the comet more visible. The coma takes in more light then it reflects it but it does reflect a small amount. The dust tail is the coolest part of a comet often being striped with different colors from different types of gases. The dust tail always faces the opposite direction of the sun because it makes an opposite force. The dust tails are gases, particles, and cosmic dust that are forced back from the coma from the opposite force, but still held in by the pull of the nucleus (center), creating an amazing thing to see across the sky.
Asteroids are metallic, rocky masses without atmospheres that orbit the Sun but are too small to be classified as planets. There are also known as "minor planets," millions of asteroids float in the asteroid belt which is located between Mars and Jupiter.
Known asteroids range in size from the largest Ceres (the first discovered asteroid in 1801) at about 600 miles in diameter down to the size of peas. Sixteen asteroids have diameters of 150 miles or greater. Most of main belt asteroids have a slightly stable orbit, revolving in the same direction as the Earth; most taking from three to six years to complete a full circle around the Sun.
Many objects have struck Earth and the Moon in the past. One theory states that an impact 65 million years ago by an asteroid or comet at least 6 miles long that made extinctions of many life forms, including the dinosaurs. Other theories suggest that much of Earth's water came from asteroids or comets that hit the planets.
Small pieces of space derby; usually parts of comets or asteroids that are ready to collide with Earth are called meteoroids. When meteoroids enter the Earth's atmosphere they turn into meteors. Most meteors burn up in the atmosphere, but some survive the heat and strike Earth. They are usually made of nickel and iron.
The Earth has been struck by many meteorites, some quite large. The adjacent image shows the Barringer Crater in Arizona . It is 1.2 kilometers across and 200 meters deep, and was formed about 49,000 years ago by a 50 meter meteorite travelling at a speed of 11 kilometers per second.
The first moons that were discovered outside of the Earth‘s moon were the Galilean moons of Jupiter, named after Galileo Galilei. The moons Io, Europa, Ganymede, and Callisto are Jupiter‘s largest and only the first four to be named the planet has 63 moons.
An interesting fact about some of the solar system‘s big moons is that most people don’t know that a few of them are volcanically active. While our moon doesn’t create lava or have any evidence of it, Jupiter’s Io and Europa, some of staturnand Neptune’s moons have been found to be volcanically active bodies.
A half moon looks like half a circle. It is sometimes called a quarter moon. This Moon has completed one quarter of an orbit around the Earth and one quarter of the moon's surface is visible from Earth.
A full moon appears as an entire circle in the sky. The full moon is given different names, depending on when it appears. For example, the "Harvest moon" is the full moon that appears close to the Autumn Equinox, occurring in late September or early October.
When two full moons happen in one month, the second full moon is called a Blue Moon. Another definition of the blue moon is the third full moon that occurs in a season that has four full moons usually each season has only three full moons.