9. Explain the following in brief 3M
a) Geoid
b) Asteroids
c) Milky Way Galaxy
Answers
Answer:
a. A geoid is the irregular-shaped “ball” that scientists use to more accurately calculate depths of earthquakes, or any other deep object beneath the earth’s surface. Currently, we use the “WGS84” version (World Geodetic System of 1984).
b Asteroids are rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. There are millions of asteroids, ranging in size from hundreds of miles to several feet across. In total, the mass of all the asteroids is less than that of Earth's moon.
Despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future.
c. The Milky Way galaxy is an immense, flat, disk-shaped collection of gas, dust, and stars that spreads around 100.000 light-years across and is several thousand light-years thick.
Key Facts & Summary
There are at least 100 billion galaxies in the universe, and the Milky Way is just one of them.
The Milky Way – out of the four types of galaxies – is a spiral barred type of galaxy.
Every star we see with our naked eyes is in the Milky Way galaxy. The only object you can see in the sky outside of the Milky Way with your naked eyes is the Andromeda Galaxy.
Answer:
The geoid (/ˈdʒiːɔɪd/) is the shape that the ocean surface would take under the influence of the gravity and rotation of Earth alone, if other influences such as winds and tides were absent. This surface is extended through the continents (such as with very narrow hypothetical canals). According to Gauss, who first described it, it is the "mathematical figure of the Earth", a smooth but irregular surface whose shape results from the uneven distribution of mass within and on the surface of Earth. It can be known only through extensive gravitational measurements and calculations. Despite being an important concept for almost 200 years in the history of geodesy and geophysics, it has been defined to high precision only since advances in satellite geodesy in the late 20th century.
Asteroids are rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. There are millions of asteroids, ranging in size from hundreds of miles to several feet across. In total, the mass of all the asteroids is less than that of Earth's moon.
Despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That's one reason scientists study asteroids and are eager to learn more about their numbers, orbits and physical characteristics. If an asteroid is headed our way, we want to know that.
The Milky Way[a] is the galaxy that contains our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. The term Milky Way is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος (galaxías kýklos, "milky circle").[19][20][21] From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.[22] Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis,[23] observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.