Center of the Solar System:
We all have heard or learned that Sun is the center point of our solar system, but that is not completely true or not true, rather it is just a reasonable approximation. The center of our solar system is the point in the space called the barycenter. Every star-planet system has its own center point, calling sun as the center point of sun and any other planet means that the sun is infinitely massive, that is completely wrong. Earth is way lighter than the sun, so the barycenter of earth and the sun is just near to the center of the sun. Jupiter is a lot heavier than the earth, so the barycenter of Jupiter and the sun is near the surface of the sun. Even the sun orbits around the shared center of mass of the solar system. As the sun contributes approx 99.8% of the mass of the solar system, the shared center of mass or barycenter of the solar system is close to the center of the sun, this causes the sun to look like it’s wobbling, just like shown in the picture below:
Matter in the Universe:
Our Universe is a big sack of mysteries and hidden matter. All the “normal matter” we can see and understand, like stars, galaxies, planets, black holes, everything visible in the universe- make up just 5% of the known universe. The other 95% is something we can’t see or understand, but we are totally aware of its existence in the universe, which we call it Dark Matter and Dark Energy.
Expansion of Universe:
Thanks to Edwin Hubble, whose observations gave us an understanding of the expansion of the Universe. Our universe is expanding at the rate beyond our imagination, around 70 km/s/Mpc – one Mpc (megaparsec) is just over 3m light-years. This actually means, the object at a distance of 1 megaparsec is moving away from us at the speed of 70 km/s. In fact, space between that object and us is expanding at a rate of 70 km/s. The farther the object is, the faster it is receding away from us. Let’s take an example of a balloon with red spots on its surface – when you blow air into that balloon the red spots move away from each other and as the balloon gets bigger and bigger, the dots get farther and farther away from each other.
Just like this, our universe is expanding and the galaxies are moving farther away from each other. Not only it is just expanding, but it is also accelerating at a faster rate. In the past, it was expanding at a slower rate than it is today. Though the expansion doesn’t mean that every galaxy is moving away from each other, it also means if some galaxies are getting closer, they are getting closer at an accelerating rate. Just like Andromeda Galaxy, the nearest galaxy to our own Milky Way Galaxy is on its way to collide into our galaxy, but don’t worry by that time Human Life may not be there to witness it.
Distance between the earth and the moon:
The distance between the earth and the moon is about 400,000 Kms and interestingly, you can fit all the planets of Solar System in the space between the earth and the moon.
We are nothing but Stardust:
After the big bang happened there were only two elements present in the universe, hydrogen and helium and nothing else. These two elements are the foundations of everything. The atoms of hydrogen and helium started concentrating at one point under the influence of gravitational force and formed a massive spiral disk bigger than our solar system. The temperature at the core surpassed 100 million degrees which resulted in detonation and gave birth to the very first stars in the universe. Other heavy elements like oxygen, carbon, and nitrogen started to forge at the core of these stars. Once the star gets bulkier enough and cannot withstand its own gravitational force it explodes and all the energy along with hydrogen, helium and all the other heavy elements fling into the universe and create other stars and all the other stuff present in the universe. This flung stuff from an exploded star is called stardust. This stardust then starts to accumulate and form various shapes to what we call planets, comets, and asteroids. Similarly, stardust from a distant exploded star traveled millions of miles with millions of tonnes of matter and heavy elements like complex carbon-based compounds, which make almost every matter present on earth even you and I. Half of the atoms that make up our bodies have formed by this stardust, hence, we have stardust in us as old as the universe.