Explanation

The Earth was formed about 4.5 billion years ago.

Additional information:

• Method Used: Radiometric dating
• Oldest Materials: Meteorites and ancient Earth rocks
• Scientific Consensus: Supported by geology and astronomy

Last verified on 16-01-2026

Explanation

Luminosity is the total amount of energy a star emits per second.

It depends on the star’s size and temperature.

Brightness is how bright the star appears from Earth, which can vary with distance.

Magnitude is a scale to measure stellar brightness.

Explanation

A comet moves fastest when it is closest to the Sun, called perihelion.

The Sun’s gravity pulls the comet strongly, increasing its speed.

At aphelion (farthest point from the Sun), its speed is much slower.

This follows Kepler’s laws of planetary motion.

The increase in speed also causes the comet’s tail to become more visible.

Explanation

Explanation

• Comets are small celestial bodies made of ice, dust, and rock.
• When they approach the Sun, they form bright tails of gas and dust.

• Often called “dirty snowballs” due to icy composition.
• Comets follow highly elliptical orbits around the Sun.

Last verified on 19-01-2026