Universe MCQ Question and Answer | Geography MCQ Question

The sky appears blue because the sunlight is scattered by the gas molecules in the atmosphere - a phenomenon known as Rayleigh scattering - named after the discoverer - a British physicist who also discovered Argon - Lord Rayleigh (1842-1919). So, if there was no atmosphere, the sky would appear black.

The planet Mercury is often cited as the most difficult of the five brightest naked-eye planets to see. Because it's the planet closest to the Sun, it never strays too far from the Sun's vicinity in our sky.

The correct sequence of planets in the descending order of their equatorial diameter is Uranus, Earth, Mars, Mercury.

The Foucault pendulum is a simple device named after French physicist Léon Foucault and conceived as an experiment to demonstrate the Earth's rotation.

Our solar system is so big it is almost impossible to imagine its size if you use ordinary units like feet or miles. The distance from Earth to the Sun is 93 million miles (149 million kilometers), but the distance to the farthest planet Neptune is nearly 3 billion miles (4.5 billion kilometers).

Mars is often called the 'Red Planet' because it appears in the sky as an orange-red star. The colour caused the ancient Greeks and Romans to name it after their god of war. Today, thanks to visiting spacecraft, we know that the planet's appearance is due to rust in the Martian rocks.

The statements that are correct with regard to Milky Way are - it is a spiral galaxy and the solar system resides in one of its spiral arms.

Neptune has 14 moons, all named after various sea gods and nymphs in Greek mythology. Almost half of Neptune's moon discoveries occurred decades after NASA's Voyager 2 spacecraft swung past the planet and its system, demonstrating how far telescope technology has progressed.

All of Neptune's moons derive their respective names from Greek mythology. They are: Naiad, Thalassa, Despina, Galatea, Larissa, Hippocamp, Proteus, Triton, Nereid, Halimede, Sao, Laomedeia, Psamathe and Neso. This arrangement has been done keeping in mind their closeness to their planet.

It's the time it takes for a distant star to return to the same position in the sky, and it differs from the solar day because the Earth revolves around the Sun as it rotates on its own axis; there is one more sidereal day than solar day each year. A sidereal day is approximately 23 hours, 56 minutes, 4.0916 seconds.

Venus is the closest planet to Earth (it's also the most similar in size). But its proximity to our planet depends on the orbits of both. The two planets travel in ellipses around the sun, and so the distance between them is constantly shifting.