7 Facts about the stars

Introduction

The stars have fascinated humanity for millennia, captivating our imaginations and inspiring countless myths, legends, and scientific inquiries. But what do we need to know about the stars in the first place?

In this article, we delve into seven fascinating facts about stars, shedding light on their nature, diversity, and extraordinary significance in the cosmos. Join us on a journey through the realms of stellar phenomena, where we uncover the mysteries that have captivated humanity since the dawn of time.

1. Stars Are Massive

And when I say massive stars, I mean massive! Of course, not all stars are bigger than the Sun. For example, stars known as red dwarfs can have a radius less than one-tenth that of the Sun. But the largest stars, such as red supergiants, can have radii hundreds or even thousands of times greater than the Sun's.

To put this into perspective, if the Sun were the size of a typical grapefruit, a red supergiant like Betelgeuse would be the size of a small town.

The largest known star is VY Canis Majoris, which is 2000 times bigger than our Sun, and our Sun is large with a diameter of 864,938 miles. When we consider the mass of some of the biggest stars we know of we usually count them as multiples of our Sun, For example, Carinae A is 120 times the mass of our Sun but it is nowhere near the biggest we know of.

2. Stars Are Held Together by Gravity

Stars are like giant balls of hot gas held together by its gravity. Gravity pulls all the gas toward the center of the star.

When a star forms, it causes gas and dust to squeeze together, creating heat and pressure at the center. Once the temperature and pressure become high enough, nuclear fusion starts, producing energy that pushes outward.

This outward pressure balances the inward pull of gravity, keeping the star stable. Throughout their lives, stars maintain this balance. When a star runs out of fuel, gravitational collapse happens, forming different objects like white dwarfs, neutron stars, or black holes, depending on its size.

Without gravity, bits of the stars would be flung all over the place, and fusion would never happen.

3. Stars Provide All the Energy for Life on Earth

Everything on our planet Earth is here because of the stars—one exact star, to be precise—our nearest star, the Sun. Every chemical on the planet was created in a star. 

The Sun provides the energy for life on Earth through a process called nuclear fusion. This energy radiates out from the star in the form of light and heat. On Earth, sunlight is essential for photosynthesis, the process where plants convert sunlight into energy to grow. This energy sustains all life on the planet, powering ecosystems and driving the Earth's climate system.

Without the energy from the Sun, life as we know it would not be possible.

4. Stars Are Out in the Daytime as Well

Stars can be seen during the daytime. But the primary reason we can't spot them with the naked eye is because the Sun's light outshines them, making them difficult to detect against the bright sky.

However, some of the brightest stars and planets can become visible during certain conditions, mainly when the sky is very clear and the Sun is low on the horizon.

Additionally, during a solar eclipse, when the Moon partially blocks out the Sun's light, stars may briefly become visible in the darkened sky.

5. The Milky Way Has Over 400 Billion Stars

Nobody knows how many stars are out there in the universe, but our home - the Milky Way galaxy alone- is estimated to contain anywhere from 100 to 400 billion stars. That is a number our human mind has difficulty comprehending.

Another amazing fact is that each star is different; there are billions of them, but they are all unique. To be a perfect star like our Sun, the star must be in perfect balance.

In this context, "perfect" means a state of equilibrium where the inward pull of gravity is exactly countered by the outward pressure from nuclear fusion occurring in its core. Gravity pulls the star's mass inward, while the energy generated by fusion pushes outward. When these forces are balanced, the star remains stable, maintaining its "perfect" state. The star could expand, contract, or even explode if this balance is disrupted.

6. People Have Used the Stars to Navigate for Years

The positions of the stars are so reliable that humans have used them for millions of years as a reference point for navigation.

Not only do humans use the stars, but the animal kingdom also employs them for navigation. Insects and birds use the positions of the stars to find their way around the planet. For example, the indigo bunting, a small songbird, migrates at night and uses the patterns of the stars in the northern sky to guide its journey.

Similarly, the dung beetle can navigate in a straight line by using the Milky Way as a guide, ensuring it efficiently rolls its dung balls away from competitors.

7. Stellar Families

Many stars are not solitary but exist in multiple-star systems, in which two or more stars orbit around a common center of mass. These systems can range from binary star systems, consisting of two stars orbiting each other, to more complex arrangements with multiple stars.

For instance, the Alpha Centauri system, the closest star system to our Solar System, is a triple star system comprising three stars: Alpha Centauri A, Alpha Centauri B, and Proxima Centauri. Binary systems are quite common, and about half of all stars in our Milky Way galaxy are estimated to be part of binary or multiple-star systems.

Luhman 16, the third closest star system to our Solar System, contains two brown dwarfs.

Bonus Fact

Nebulae, often called stellar nurseries, are vast clouds of dust and gas where new stars are born. These regions serve as incubators for star formation, with gravitational forces gradually pulling material together to form young stars.

In a similar way, naming a star can be a way to mark the birth of a new relationship or milestone. It symbolizes the beginning of something unique and enduring, much like the stars that emerge from these cosmic nurseries, creating a lasting bond between the individual and the celestial object.

Conclusion

1. Stars, ranging from minuscule red dwarfs to colossal red supergiants, anchor the universe with their gravitational pull and sustain life on Earth through the energy they emit.
2. While stars typically fade against the bright light of the Sun during the day, they occasionally can be seen in the daytime during unique events like solar eclipses.
3. The Milky Way galaxy hosts an astounding 400 billion stars, and how many are there in total still remains a mystery.
4. Across millennia, stars have guided both humans and animals, serving as unchanging navigational aids.
5. Stars are not always floating alone in the vast universe. Some are in groups where two or more stars orbit around each other, called binary systems, while others are in more complex groups with multiple stars.

References

1. National Geographics - "Everything you wanted to know about stars"
2. NASA - "Star Basics"
3. Wikipedia - "Star"