Aastronomy

What is Astronomy?

Astronomy is the study of everything in the universe beyond Earth’s atmosphere including objects we can see with our naked eyes, like the Sun , the Moon, the planets, and the stars . It also includes objects we can only see with telescopes or other instruments, like faraway galaxies and tiny particles. And questions about things we can't see like dark energy.

Astronomy is one of the oldest scientific disciplines that has evolved from thebeginning of counting stars and charting constellations with the naked eye to the impressive showcase of humankind's technological capabilities. Despite all progress, astronomers are still working hard to understand the nature of the Universe and humankind's place in it.

As the depths of the sky opened in front of our increasingly sophisticated telescopes, and sensitive detectors enabled us to spot the weirdest types of signals, the star-studded sky that our ancestors gazed at objects including black holes, white dwarfs, neutron stars and supernovas.

At the same time, the two-dimensional constellations that inspired the imagination of early sky-watchers were reduced to an optical illusion, behind which the swirling of galaxies hurtling through spacetime reveals a story that began with the Big Bang some 13.8 billion years ago.

What are the big ideas about astronomy?

1. When we look up at the night sky, we see patterns and want to explain them

Early observers looked atsky in night and noticed patterns in the stars . These patterns, which we call constellations, might appear to change place, but they don’t change shape.

2. The sky is vast and distances between objects can be very large

Stars look tine to us but they are not.They're huge, burning balls of gas, like our Sun. They just appear small because they are so far away. The nearest star to our solar system is 4 light years away, which is 20 trillion miles.

3. Everything in space is moving all the time

Earth is spinning. If you were standing on the equator, you and the spot under your feet would be rotating at a speed of about a thousand miles per hour. But Earth is also orbiting around the Sun, moving even faster: 67,000 miles per hour. And the Sun itself is moving around the center of our galaxy, carrying everything in the solar system with it, at a rate of 490,000 miles per hour.

4. Gravity holds everything together

We don’t fly off while the earth is moving because of Gravity. It is the force of attraction between all objects in the universe. An object’s gravity depends on its mass —its total amountof matter.

5. There’s much more to light than our eyes can see

Light is a form of energy called electromagnetic radiation. We see objects because they reflect, or bounce, light into our eyes. But there’s a whole spectrum of electromagnetic radiation, and our eyes can detect only a teeny, tiny portion of it. That portion—visible light—consists of different wavelengths of light that we perceive as different colors.

6. The universe contains mysterious, invisible stuff

7. Dark matter doesn't give off light like a galaxy or absorb light like a black hole. Scientists know it exists because it has a gravitational pull, just like normal matter.

8. Dark energy is a mysterious pressure working in opposition to gravity, pushing matter apart.