Phases of the Moon and Constellations - Class 4 Notes

Moon

a) The Moon is the closest object to Earth in space. When it gets dark outside, the Moon is the brightest thing we can see up in the sky.
b) The Moon has different kinds of landscapes. It has tall mountains, just like we have on Earth. It also has flat areas called plains, and they are covered in sand-like material.
c) Unlike Earth, the Moon doesn't have any air to breathe or water to drink.
d) The Moon doesn't produce its own light. Instead, it reflects the light from the Sun.
e) The Moon goes around the Earth in a big circle called an orbit. The Moon takes about 28 days to complete one full orbit around our planet.
f) Moon's gravity affects the ocean tides on Earth. It pulls the water towards it, creating high and low waves.

Phases of the Moon

As the Moon moves around the Earth, different parts of it get light from the Sun. We can only see the part of the Moon that is lit up. It looks like the Moon's shape is changing every day. We call these changes the phases of the Moon.

New Moon (0 days): Sometimes we can't see the Moon at all, and that's called the new moon. It happens when the Sun, Moon, and Earth are in a line, and the side of the Moon facing us is not lit up.

Waxing Crescent Moon: After the new moon, a small sliver of the Moon becomes visible. This is the beginning of the waxing crescent phase.

First Quarter Moon: As the Moon continues to move, it reaches the first quarter phase. We call it the "first quarter" because we can see exactly half of the Moon's lit-up side. It looks like a half-circle shape.

Waxing Gibbous Moon: After the first quarter, the lit-up part of the Moon keeps getting bigger. This phase is called the waxing gibbous moon. It's bigger than a half-circle but not quite a full circle.

Full Moon (14 days): At around two weeks after the new moon, we have a full moon. When the Moon, Earth, and Sun are in a line, with the Earth in the middle, we see the full moon. It looks like a big, round circle in the night sky.

Waning Gibbous Moon: After the full moon, the lit-up part of the Moon starts getting smaller. This is called the waning gibbous moon. It's still big but not as round as a full moon.

Third Quarter Moon: The third quarter moon occurs when we can see exactly half of the Moon's lit-up side again, but this time it's the opposite side compared to the first quarter. It looks like a half-circle shape again.

Waning Crescent Moon (28-30 days): As the Moon continues to move, less and less of its lit-up side is visible. This phase is called the waning crescent moon. Sometimes you can even see a faint glow of the dark part of the Moon, which is called Earthshine.

The phases of the moon keep repeating in the same order. After the waning crescent, it goes back to the new moon, and the cycle starts again.

Asteroids

a) Asteroids are big chunks of rocks that orbit around the Sun, located between the planets Mars and Jupiter.
b) They are like huge space rocks. We also call them minor planets or planetoids.

Comets

a) Comets are made up of many rocks and metals stuck together, and they are covered in frozen ice and gases.
b) They are like a big collection of icy particles floating in space. Sometimes, when they get closer to the Sun, the ice melts and creates a glowing tail.

Meteors (Shooting Stars)

a) Meteors are very common and we often call them "shooting stars." They are celestial objects in the sky that appear as bright streaks of light for a short moment.
b) They are not really stars but small objects like rocks or dust that burn up as they enter the Earth's atmosphere.

Stars

a) When we look up at the night sky, we see thousands of twinkling stars.
b) Stars are like big balls of hot, burning gas. They give off heat and light.
c) They are really far away from us, and there are millions and millions of stars in the universe.

Constellations

a) Sometimes, groups of stars in the sky seem to make patterns or shapes. We call these groups of stars constellations.
b) There are 88 different constellations that people have named. They often have names based on creatures or people from myths and legends.
c) Some well-known constellations are Leo (the Lion), Ursa Major (the Big Bear), and Orion.

Artificial Satellites

a) Apart from stars, there are also man-made objects that revolve around the Earth. We call them artificial satellites.
b) These satellites are really helpful for communication, weather forecasts, and navigation.
c) For example, Hubble Space Telescope, INSAT 1A, and GPS satellites are some of the satellites used for these purposes.