17 space-related words you need to know

A list of terms that many of us might find useful to brush up on

By Shashi Tharoor

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Published: Thu 7 Sep 2023, 6:13 PM

Last week, we reviewed some basic terms used in every discussion about space in the mass media. But there are more we should know. I won’t waste this space defining obvious terms that most schoolchildren are familiar with, but here’s the first half of a list of terms that many of us might find useful to brush up on:

Antimatter: Antimatter is made up of tiny particles that are the opposite of normal “matter”, or material. When matter meets its antimatter equal, they are both destroyed, releasing a lot of energy.

Asteroid: Asteroids are chunks of rock and metal left over from when our solar system was formed. Most can be found buzzing about between Mars and Jupiter, a region of space called the Asteroid Belt, heavily populated by asteroids, comets (explained below) and dwarf planets, objects in the solar system bigger than comets or asteroids but smaller than planets. Our solar system has five dwarf planets, including Pluto, which was recently downgraded from the status of a full planet. (When I was a child, I learned the names of the planets in the order of their distance from the Sun by remembering a simple mnemonic: “My Very Educated Mother Just Showed Us Nine Planets”. This reminded me, in order, of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Pluto. I will always lament the loss of this indispensable tool with the snuffing out of Pluto’s pretentions!)

Atmosphere: A layer of gases surrounding a planet or a moon. Earth’s atmosphere contains the oxygen we breathe.

Big Bang: A theory that states that, some 14 billion years ago, the entire universe was inside a bubble thousands of times smaller than a pinhead. Then it exploded and the universe was born.

Binary System: A system of two stars orbiting around each other. (Four out of every five points of light we see in the night sky are not one star, but two or more.)

Black Dwarf: The very last phase in the lifecycle of a star like our sun. When the star has cooled down so much that it no longer shines at all, it becomes a black dwarf.

Black Hole: It is formed when a massive star dies and is squashed into an indescribably tiny space. Black holes’ very strong gravity can even swallow up light. A galaxy with an active supermassive black hole at its centre is called a Blazar.

Brown Dwarf: Brown dwarfs are dubbed “failed stars” by some astronomers, because unlike stars, they never become hot enough to start giving off energy.

Comets: Made up of ice, dust and rock, these objects come from the outer regions of the solar system and orbit the sun. They shoot through space with their long, streaming tails, lending their names to space projectiles and aircraft. These ancient objects are leftovers from the formation of the solar system 4.6 billion years ago.

Corona: Nothing to do with the notorious virus, the corona is an envelope of blisteringly hot gas surrounding the sun.

Dark Energy: It is the main ingredient of the universe. It opposes gravity, causing galaxies to fly apart from each other faster.

Dark Nebulae: Dark nebulae look like holes in the night sky, since they are completely black. However, they aren’t empty, but are composed of thick clouds of cosmic gas and dust that block out light.

Dwarf Galaxy: Dwarf galaxies are much smaller than normal galaxies. They are made up of just a few billion stars rather than hundreds of billions.

Eclipse: What happens when the Earth passes between the Moon and the Sun, and the Moon becomes completely cloaked in shadow, is a lunar eclipse. When the Moon passes between the Sun and Earth and blocks out the Sun’s light, we have a solar eclipse.

Exo-planet: An extrasolar planet (exo-planet for short) is a planet that orbits a star beyond our Solar System.

Gamma Rays: They are the most energy-producing light, yet they are invisible.

Gravity: The force that attracts all objects that have mass, made the apple fall on Newton’s head, keeps your feet on the ground and maintains the Earth and all the other planets in orbits around the Sun.

More next week!


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