Our Universe (HBBVS)

Our solar system is situated in Orion Arm of Milky Way galaxy.

Sun is the closest star to Earth.

Different constellations appear in the night sky at different time periods of the year due to revolution of Earth.

Photosphere is the part of the sun we actually see. Most of the white light that makes our world visible comes from photosphere of the sun.

Cosmology is the study of the universe.

The periods of rotation and revolution of Mars are equal.

During a total solar eclipse, corona is the only visible part.

Mercury, Venus, Earth and Mars are the outer planets. They have none or very few satellites or moons and lie between the sun and the asteroid belt.

Venus revolves in a clockwise direction from East to West. So, the sun rises from the East and sets in the West.

We can determine the temperature of the stars by determining their colour. Hottest stars are blue and coolest are red in colour.

Jupiter has 67 moons and it has the largest satellite, named Ganymede.

The sun exerts immense gravitational pull due to which the planets revolve around it in an elliptical orbit.

Uranus was the first planet discovered by using a telescope.

The rocks that are not burnt out completely in Earth's atmosphere and are able to reach Earth's surface are called meteorites.

Milky Way galaxy is spiral in shape.

Small solar system bodies are the components of the solar system.

Saturn is the least dense planet (its density being almost one-eighth of that of Earth). Its density is less than water.

Neptune has its surface covered with ice and the poles have pink snow of frozen nitrogen.

Dhanu is the Indian name of Sagittarius.

Venus is the hottest planet because carbon dioxide present in its atmosphere traps the heat due to its greenhouse behaviour.

The orbit of revolution of Pluto overlaps that of Neptune. Thus, Pluto is now called a dwarf planet.

When the moon comes between Earth and the sun, a solar eclipse occurs.

Waxing is the name given to the phase when the shape of the moon grows.

The moon's shadow covers only a small portion of Earth, where the eclipse is visible. As the moon moves in its orbit (at 1 km/hr), the position of the shadow changes very quickly.

Spring tides occur when moon, Earth and sun are in the same line.

Aryabhatta was the first Indian satellite launched on 19^th April, 1975.

The time period between high tide and low tide is 6 hours 12 minutes.

These satellites are used to observe distant planets, galaxies and other outer-space objects.