1. Space and Universe
1. Space and Universe
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Explain the concept of the universe as a vast space that includes all celestial bodies, matter, and everything that exists
Explain the concept of the universe as a vast space that includes all celestial bodies, matter, and everything that exists
Hey there, young explorers! Let's embark on an incredible journey to a place that's out of this world—space and the universe. Imagine looking up at the night sky and wondering about the twinkling stars, mysterious planets, and galaxies far, far away. Well, that's what we're going to dive into in this lesson!
The atmosphere (the layer of air encircling our planet) disappears at a height of about 100 kilometres, marking the beginning of 'outer space.’ Space appears as a huge, dark, star-studded vastness in this airless universe.
Fig. 1.1 Outer space beyond Earth
Everything that we can touch, sense, measure, or detect is part of the universe. It consists of life, planets, dozens of moons, asteroids, stars, galaxies, clouds of dust, light, and much more.
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When we travel beyond Earth, we find other planets in our solar system—like Mars, the red planet with giant dust storms; Jupiter, the biggest planet with spinning storms; and Saturn, famous for its beautiful rings made of ice and rock!
Outside our solar system, there are millions of stars and planets that belong to huge star families called galaxies. We live in one of these galaxies—it’s called the Milky Way!3
There are billions of galaxies in the universe, and each one has millions or billions of stars. People often think that the space between the celestial bodies is entirely vacant, but that's not quite accurate. The immense empty spaces between stars and planets are actually filled with thinly spread out gas and dust. And that's not all—space is also filled with things like light, heat, magnetic fields, and energetic particles, making it a truly happening place.
The size of the universe is enormous. A current jet fighter would need more than a million years to travel to the closest star to the Sun.
Since we cannot see the boundary of the universe, if there is one, no one knows its exact size. The size of the universe has changed over time. According to scientists, the universe has been rapidly expanding. Therefore, compared to when the universe was extremely young, the amount of space that we can see today is billions of times larger. As the distance between them widens, the galaxies are also getting farther away.
Fig. 1.2 first image from James Webb Space Telescope: galaxy cluster SMACS 0723
Watch this video2 to learn about our universe:
Vid. 1.1 Our Universe
Glossary
atmosphere: a layer of gases surrounding a planet or other celestial body.
universe: everything, including all of space, and all the matter and energy that space contains.
celestial bodies: any natural body outside of earth’s atmosphere.
Summary
Outer space begins about 100 kilometres above Earth's surface, where the atmosphere ends.
The universe encompasses everything, including life, planets, stars, galaxies, and more. It's a massive, all-encompassing entity.
In the universe, there are billions of galaxies, each with millions or billions of stars. The space between celestial bodies isn't entirely empty; it contains thinly spread gas and dust, along with light, heat, magnetic fields, and energetic particles.
The universe's size is incredibly vast.
The exact size of the universe is unknown, as we can't see its boundary, but it has been expanding rapidly over time.
Extensions
Watch this video to learn more about how the universe is expanding: link
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