Olympiad Test Level 2: Our Earth and Universe- 1 - Class 6 MCQ

• The sun, the moon and all those objects shining in the night sky are called celestial bodies.
• These celestial bodies are not visible in the daytime because of the bright light of the sun.
• Any natural body outside the Earth’s atmosphere is known as a celestial body.

Correct option is C. Greek

Neptune is the farthest planet from the sun and one of two "ice giants" in our solar system. The cold, blue planet is about 30 times farther away from the sun than Earth and takes around 165 Earth years to complete a single orbit around our star.

The year is divisible by 400, then it is a leap year. So 1996 was a leap year, but 1997, 1998, and 1999 were not. The year 2000 was a leap year because even though it is divisible by 100 it's also divisible by 400.

• Magma is an extremely hot liquid and semi-liquid rock located under Earth’s surface. It is a mixture of molten or semi-molten rock, volatiles, and solids.
• Besides molten rock, it may contain suspended crystals and dissolved gases. When magma flows onto Earth’s surface, it is called Lava.

• Meteorology is the study of the atmosphere. 
• A meteorologist is an individual with specialized education who uses scientific principles to explain, understand, observe or forecast the earth's atmospheric phenomena. 
• They also study how the atmospheric and weather conditions affect the earth and its human inhabitants.

• About 90 percent of the mass in the Milky Way’s gravitational field is made up of dark matter, so the luminous stars gas and dust of the galaxy are embedded at the center of a huge, roughly spherical dark matter halo of more than a million light-years across. There is an object at the center of the Milky Way called Sagittarius A-star which emits much more X-rays and radio waves than expected for a star-sized body. 
• Much of the Milky Way galaxy is blocked from our view on Earth due to the barriers created by dusty gas clouds blocking much of the light. Using infrared, microwave, and radio astronomy techniques, it is possible to penetrate much of this dusty fog. However, that too allows us only detect only half of the stars and gas.

• Joseph Priestley was hugely productive in research and widely notorious in philosophy. He invented carbonated water and the rubber eraser, identified a dozen key chemical compounds, and wrote an important early paper about electricity. 
• He found that air is not an elementary substance, but a composition, or mixture, of gases. The world recalls Priestley best as the man who discovered oxygen, the active ingredient in our planet's atmosphere.

Moon completes one revolution in 29.53 days. Thus each phase of the moon repeats after 29.53 days which is approximately equal to an average standard month.

The constellation Cassiopeia, Queen of Ethiopia, can be seen in the northern hemisphere all year long. Cassiopeia is one of the most easily recognizable constellations due to its distinctive W or M shape, depending on the time of year and the viewer’s location.