Space. Solar system

Where are we in the universe?

Talking in general, we live in the Galaxy. The word ‘galaxy’ has Greek origin and it can be translated ‘milky’ from the Greek language. There is a Greek myth about Hera, the Goddess of Heaven, who sprayed (by accident) her milk across the sky. That’s how the Milky Way Galaxy appeared.

We live in the second largest galaxy, the Milky Way Galaxy. It is a spiral galaxy. It contains at least a hundred billion stars. They are moving together with concentrations of gas and dust particles, forming spiral-shaped swirls. These swirls are called arms and each arm has its own name.

Our Solar system is located on the inner edge of the Orion Arm, and it is home to our planet Earth, where we live on.

Almost all stars and other objects that we can see in the sky belong to the Milky Way Galaxy. But a huge quantity of stars of the Milky Way Galaxy is just impossible to observe from the Earth and they are not visible from our planet.

Do you remember how many stars in the Milky Way Galaxy?

At least a hundred billion, but some scientists suggest that it can be up to four hundred billion stars. And we can see from any one point on the globe only about 2, 500 and no more. But the Milky Way is constantly losing stars and producing new ones all the time.

Today we can’t take a picture of all the Milky Way Galaxy, and we can’t even make a picture of our Orion Arm. Any of the beautiful pictures that you can find on the internet is just an imaginary picture of an artist or a picture of another spiral galaxy. Why so?

Because we can’t take a picture of the whole house when we’re inside our room. And we are inside the galactic disk, about 26,000 light years from the center.

However, this doesn’t mean that we can’t take breathtaking images of the Milky Way from our vantage point!

When we look in the night sky we can see our Milky Way Galaxy as a band full of twinkling lights that stretches across the sky. It is easier to see it when air is absolutely clean and dark, so go away from the smoggy city air with bright lights. Then you can see a lot of stars that form different constellations.

The word ‘constellation’ comes from Latin: stella-meaning ‘stars’ and con-, meaning ‘together’. So, a constellation is a group of stars, usually in a recognizable shape or pattern.

Together, the stars look like a picture. Some examples of constellations are Ursa Major, Perseus and Andromeda, Corona Borealis, Lyra and Scorpius. They take their names from Greek mythology, like most of the constellations in the Northern hemisphere. Nowadays there are 88 officially recognized constellations, covering the entire sky.

But we can notice not only separate stars or constellations, but whole galaxies as well, except our Milky Way Galaxy, of course. Galaxies can be seen as diffuse patches of light so they are hard to trace unless the sky is very dark. But we can see a few other galaxies without using a telescope, though.

One of the most beautiful galaxies we can see with the naked eye is the Andromeda Galaxy. It is easy to see it from the place we live in, I mean the northern hemisphere. And November is the perfect time to hunt down this distant object.

How to see the Andromeda Galaxy?

Well, well, well… Let’s try to do it together. Facing the northeast autumn evening sky, we need to look for 3 constellations: Pegasus, Cassiopeia and Andromeda.

By the Greek mythology, Pegasus was the flying horse. Pegasus is one of the easier to locate of the three, as it looks like a giant rectangle; this is the Great Square of Pegasus. The Queen Cassiopeia was the wife of king Cepheus according to the Greeks, and she was beautiful but also arrogant and vain. Cassiopeia is even easier to locate, because it looks like a giant "W". Andromeda lies between them. Andromeda was a princess and daughter of Cassiopeia; she was rescued from a monster by Perseus.

Then we should put a trace from the stars on the W bottom down to the stars of Andromeda constellation. And on this line you'll notice an oval of faint light. This is the Andromeda Galaxy. But if you use a telescope, you can see it much better. And you can notice that the Andromeda Galaxy is the other spiral galaxy besides the Milky Way. But it is home to at least 300 billion suns, and it is about 3 times as large as the Milky Way. Andromeda is also known as Messier 31, or M-31. This magnificent island of stars lies about 2.6 million light-years away.

We can see a few other galaxies without using a telescope. They are our nearest neighbours, but they are easy to see from the southern hemisphere, for example, in Australian or African sky.

They are the Large and Small Magellanic Clouds (Magellan or Portuguese). Just look at this beauty.

But let’s return to the Earth and have a glance at our solar system. It consists of the Sun and planets; this is our planet Earth and the Moon. But there are other planets and moons. Actually, in our solar system there are 61 different moons. There are many dwarf planets (or plutoids). There are comets. Comets are small, icy bodies that orbit the sun. They have very long tails. There are asteroids that are also called minor planets; they are rocky or metallic objects.

There are meteoroids. Meteoroids are small bodies. They travel through space. They can be stony, metallic, or both stony and metallic and they are smaller than asteroids. Most are very tiny. Meteoroids burn if they trap to Earth’s atmosphere and we start calling them meteors. And if they fall down to the Earth’s surface and became stones, we call them meteorites.

Let’s look at this transformation.

We have already known that the Sun is the center of our Solar system; the planets that orbit the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. There’s also Pluto. It is considered to be a planet, but from 2006 it is classified as a plutoid, or a dwarf planet. Asteroids most of which orbit the Sun is situated in the asteroid belt between Mars and Jupiter.

All these objects are orbiting the Sun.

Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Asteroid, meteor, galaxy, constellation…. Uh… So many names!

Listen, I know one easy way to remember all the planets and their order (plus Pluto, of course). It is the mnemonic – you should just remember the phrase:

"My Very Excellent Mother Just Sent Us Nine Pizzas", and the first letter of each of these words represents a planet - in the correct order.

Let’s start! My – ‘m’ – do you remember the first planet? Mercury. Notice a sign to the right of each name – it is an astronomical symbol of each planet that professional astronomers and astrologers use.

Very – v – and the planet Venus.

Excellent – letter ‘e’ – and our planet Earth.

Mother gives us letter ‘m’ and planet Mars.

We take first letter 'J' and it is Jupiter. Sent – ‘s’ – Saturn.

‘U’ we have to name the next planet. It is Uranium.

Nine’s first letter is ‘N’ and the 8th planet Neptune.

And Pizzas gives us Pluto.