The scale and wonder of our universe is difficult for the human mind to fully comprehend. Even with our limited understanding, scientists have discovered some astonishing facts about the cosmos that showcase its bizarre and beautiful nature. From mind-bendingly large celestial bodies to the mysterious dark matter that pervades everything, here are 10 fascinating facts about our universe.
- 1 1. There Are More Stars in the Universe Than Grains of Sand on Earth
- 2 2. The Universe is Incomprehensibly Massive and Expanding
- 3 3. Supermassive Black Holes Exist at the Centers of Most Large Galaxies
- 4 4. At Under 2.9% Mass, the Ordinary Matter Humans are Made of is a Tiny Fraction of the Universe
- 5 5. There are More Planets Than Stars in Our Galaxy
- 6 6. The Coldest Known Place in the Universe Exists in a Lab on Earth
- 7 7. A Year is Not 365 Days Everywhere in the Universe
- 8 8. The Universe Was Once the Size of a Grapefruit
- 9 9. Distant Galaxies are Moving Faster Than the Speed of Light
- 10 10. Empty Space is Not Actually Empty
- 11 Comparisons of Amazing Facts About the Universe
- 12 FAQ About Amazing Universe Facts
- 12.1 How many stars are estimated to exist in the total universe?
- 12.2 What are supermassive black holes and where are they found?
- 12.3 What is dark matter and why is it important in cosmology?
- 12.4 How hot was the universe at the time of the Big Bang?
- 12.5 Why can we see some galaxies moving faster than light speed?
- 12.6 Why do physicists believe empty space is never actually empty?
- 12.7 How many planets are estimated to exist just in our Milky Way galaxy?
1. There Are More Stars in the Universe Than Grains of Sand on Earth
Estimates suggest there are around 100 billion trillion stars in the observable universe. That’s a ‘1’ followed by 24 zeros, or 1,000,000,000,000,000,000,000,000. For comparison, the total number of sand grains on all the world’s beaches and deserts is only around 7.5 x 10^18 grains, or 7 quintillion 500 quadrillion. The multitudes of stars vastly outnumber even grains of sand on our planet.
2. The Universe is Incomprehensibly Massive and Expanding
The observable universe spans a diameter of 93 billion lightyears containing at least two trillion galaxies. Since the Big Bang 13.8 billion years ago, it has been continually expanding, with galaxies hurtling away from each other at extraordinary speeds. In fact, most of the universe is already beyond what we can observe since its light has not had time to reach us yet. And the total size of the full unobservable universe may be infinitely larger.
3. Supermassive Black Holes Exist at the Centers of Most Large Galaxies
Black holes are the most gravitationally intense objects known to exist, capable of warping spacetime itself. Most large galaxies including our own Milky Way contain supermassive black holes many millions of times the mass of the sun at their cores. Their powerful gravity is thought to play a major role in galactic evolution. The largest known black hole in the enormous galaxy Messier 87 has a mass of 7 billion suns.
4. At Under 2.9% Mass, the Ordinary Matter Humans are Made of is a Tiny Fraction of the Universe
The atoms that make up stars, planets, and living beings only constitute 4.9% of the observable mass and energy in the universe. The other 95.1% is comprised of dark energy (68.3%) and dark matter (26.8%). Dark matter is an unknown invisible substance only detected indirectly by its gravity, while dark energy causes the accelerating expansion of the universe. Identifying these mysterious components remains one of the greatest puzzles in physics.
5. There are More Planets Than Stars in Our Galaxy
The Milky Way contains over 100 billion stars, but recent exoplanet surveys indicate there may be as many as 300 billion planets just in our home galaxy. This means there are at least 3 planets for every star on average. There are likely billions of potentially habitable rocky worlds based on this galactic census, making the possibility of extraterrestrial life seem more promising than ever before.
6. The Coldest Known Place in the Universe Exists in a Lab on Earth
At just one billionth of a degree above absolute zero (-273.15 ̊C), the Boomerang Nebula observed by the ALMA telescope in 2013 is the coldest known place in the universe. Even more incredibly, physicists at MIT have cooled molecules in their laboratory down to half a billionth of a degree above absolute zero using lasers. That’s more than 100 million times colder than the cosmic background radiation prevalent across the universe.
7. A Year is Not 365 Days Everywhere in the Universe
Because space and time are relative, the passage of a year depends on an observer’s precise location. Due to differences in orbital periods and velocities, a year on Mercury is just 88 Earth days long while a year on Venus is 225 Earth days long. Even on Earth, time moves minutely slower at higher altitudes than sea level due to less gravitational time dilation, meaning GPS satellites orbiting above experience a tiny difference in the length of a year.
8. The Universe Was Once the Size of a Grapefruit
Physicists estimate the entire universe at the time of the Big Bang 13.8 billion years ago was compressed to the size of a single extremely hot and dense speck between 1 and 100 millimeters. In the tiniest fraction of a second, that primordial grapefruit-sized speck of a universe inflated exponentially to railroad car size and beyond, expanding rapidly into the vast cosmos we now inhabit.
9. Distant Galaxies are Moving Faster Than the Speed of Light
Due to the mind-bending expansion of spacetime, very distant galaxies are moving away from us faster than the speed of light. This does not violate physics since no information is traveling through space faster than light locally. Still, spotting galaxies exceeding light speed illustrates that our intuitions about velocity and distance break down at cosmic scale. The universe is larger and stranger than our common senses assume.
10. Empty Space is Not Actually Empty
According to quantum field theory, the bare vacuum of empty space is not blank nothingness but rather a dynamic realm bursting with subatomic particles constantly popping in and out of existence. On tiny subatomic scales, empty space resembles a frothing foam of quantum activity governed by probabilities rather than certainties. This inherent vacuum energy is believed to contribute to the accelerated expansion of the cosmos.
Comparisons of Amazing Facts About the Universe
Fact | Description |
---|---|
More stars than grains of sand | 100 billion trillion stars vs only 7.5 x 10^18 grains of sand on Earth |
Scale of the universe | Observable universe diameter is 93 billion lightyears with over 2 trillion galaxies |
Supermassive black holes | Most large galaxies contain supermassive black holes millions of times the sun’s mass |
Ordinary matter is a tiny fraction | Atoms constitute just 4.9% of mass-energy in universe compared to 68.3% dark energy and 26.8% dark matter |
More planets than stars | Estimated 300 billion planets in the Milky Way compared to 100-400 billion stars |
Coldest place exists in a lab | One billionth degree above absolute zero achieved on molecules in an MIT lab |
Different years across universe | Year lengths vary from 88 days on Mercury to 225 days on Venus due to relativity |
Early tiny universe | At the Big Bang, the universe was the size of a hot dense grapefruit speck |
Galaxies exceeding light speed | Distant galaxies moving faster than light speed away from us due to spacetime expansion |
Quantum activity of empty space | Empty space buzzes with subatomic particles popping in and out of existence |
FAQ About Amazing Universe Facts
How many stars are estimated to exist in the total universe?
While the total size of the universe is unknown, astronomers estimate there are between 100 billion trillion (1×10^24) to 1 trillion trillion (1×10^30) stars in the observable universe alone. The true count of stars in the entire unobservable universe is likely vastly higher.
What are supermassive black holes and where are they found?
Supermassive black holes millions to billions of times more massive than the sun lie at the centers of most large galaxies. Their gravity is thought to play a major role in galactic evolution. Our Milky Way hosts the supermassive black hole Sagittarius A* with 4 million solar masses.
What is dark matter and why is it important in cosmology?
Dark matter is an unknown type of matter comprising about 27% of the universe. It does not interact with electromagnetic radiation but its existence is inferred by its gravitational effects on visible matter and background radiation. Understanding dark matter is viewed as key to formulating a complete theory of the universe.
How hot was the universe at the time of the Big Bang?
In its earliest moments, the entire universe was compressed into a single extremely hot and dense speck smaller than a grapefruit. The temperature following the Big Bang was an unfathomable one trillion degrees Celsius – much hotter than the cores of even the most massive stars today.
Why can we see some galaxies moving faster than light speed?
Due to the expansion of spacetime, very distant galaxies are moving away from us faster than light travels through space. No information or matter can locally travel faster than light, but the stretching of cosmic fabric enables far galaxies to become spaced apart at superluminal speeds.
Why do physicists believe empty space is never actually empty?
According to quantum field theory, what we think of as empty space is teeming with subatomic particles constantly popping in and out of existence. On quantum scales, empty space resembles a frothy foam of activity described by probabilities rather than certainties. Vacuum energy contributed by this activity may drive cosmic expansion.
How many planets are estimated to exist just in our Milky Way galaxy?
Based on exoplanet surveys, astronomers now think there are likely between 200-400 billion planets in the Milky Way galaxy alone, with an average of at least 3 planets for every star. This means there are more planets than stars in our galaxy and billions of potentially habitable worlds.