Astronomers estimate that there are approximately 100 billion stars in the Milky Way. With so many, there is a good chance that some of them have planets orbiting around them! So how many planets exist? One astronomer estimated that as much as one in five stars may have an Earth-sized planet or larger orbiting within its habitable zone. This means we could potentially find billions of earths within our galaxy alone!
There are solitary stars and planets in our Universe, as well as stellar systems and planetary systems like our Solar System. There are eight planets, five dwarf planets (maybe more), and many more moons qualified as dwarf planets in our solar system.
So, how big is the Milky Way, and how many planets does it have?
Are stars more plentiful than planets in our galaxy? They could be, but our Sun is home to eight planets. Therefore planets could be more abundant. It all relies on circumstance and causality; nonetheless, our galaxy, the Milky Way, is predicted to have at least 100 billion planets.
Exoplanets are a type of planet that orbit stars other than the Sun. Rogue planets are also planets that have been expelled from their planetary systems due to collisions or the death of their stars, leaving them unable to bind themselves gravitationally.
The eight planets of our Solar System, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, are the most well-known planets in our Milky Way. Pluto, Eris, Makemake, Haumea, and Ceres are among the five dwarf planets.
These are just a fraction of the billions of planets in our Milky Way galaxy. They’re not the closest or most habitable, but they’re good representations of other worlds. NASA now has over 4,000 confirmed exoplanets being examined, but there are many more out there.
How Many Planets Can Support Life in the Milky Way?
According to scientists, one out of every five stars like our Sun has at least one Earth-type planet circling it that could host life. Based on our Milky Way galaxy mapping and simulations, there are an estimated 40 billion planets in our Milky Way Galaxy that could host life.
This number, however, an average figure; there could be many more. When evaluating this, there are numerous aspects to consider. Still, one factor may alter our calculus: we can only know how life adapts and evolves based on the species that live and live on our planet.
There is no way of knowing what life in Outer Space is confined to. Thus many planets that we might consider unfriendly to humanity could be habitable to other unknown species.
All this may sound like science fiction, but there is truth in it; we have no idea how life can evolve and adapt; we have no idea its limits, shapes, and forms. We do know that life exists, that it adapts, and that it evolves.
Exoplanets are planets that exist outside of our solar system and are found in the Milky Way galaxy. Here are a few examples:
1) The first planet to be discovered was the gas giant 51 Pegasi b, orbiting around the Star 51 Pegasi.
2) The first planet found within a star’s habitable zone is a jovian-type exoplanet called Gliese 581c, found orbiting Gliese 581.
3) Kepler-22b is an exoplanet in orbit around its Sun. In this case, it orbits around the star Kepler-22, which is 2,300 light-years from Earth.
The name “exoplanet” is from the word “extrasolar planet”. That means a planet that exists outside of our solar system.
Their mass and radius often classify exoplanets. Depending on these two factors, they can be:
- terrestrial planets,
- Jovian planets
- dwarfs/brown dwarves
In the Milky Way, how many solar systems are there?
You may believe that our Solar System is unique. However, there have already been over 5,000 solar systems identified and studied. Every year, scientists discover new solar systems that are either identical to or dissimilar to our own.
Every year, they also uncover new solar systems.
With that in mind, scientists estimate that our Milky Way galaxy alone contains tens of billions of solar systems. Many others say there are as many as 100 billion.
In any event, our Galaxy contains more than just planetary systems. There are also stellar systems, which are groups of stars that orbit each other.
What is the total number of planets in our galaxy?
According to NASA, our Milky Way alone has at least 100 billion planets. Others have calculated that the Milky Way galaxy has between 100 and 200 billion planets.
Over 4,000 exoplanets have been identified so far, with more being discovered every day. These planets are either rogue planets or members of a planetary system.
Because rogue planets do not orbit a star, they are more difficult to find. Consider our Solar System, which has eight planets and at least five dwarf planets around our single Star, the Sun.
There could very well be a ninth planet, dubbed Planet X by some, but we’re still looking for it. Suppose our Sun, a single star, can have as many as eight or nine planets. In that case, our Milky Way galaxy, which includes billions upon billions of stars, must likewise have billions upon billions of planets.
What If I Told You…
The Alpha Centauri system is the nearest star system to our Solar System. It has two stars and one exoplanet and is only 4.3 light-years away. Additional exoplanets in the system are yet to be confirmed.
Proxima Centauri b, the closest exoplanet to us, orbits within the habitable zone of its parent star.
Many ancient Egyptian temples featured the Alpha Centauri system. Of course, they were unaware of the exoplanet’s presence, but their temples were designed to point at the Star’s location.
In the early 1990s, the first exoplanets were identified. Since then, the number of exoplanets discovered has doubled every 27 months, and it continues to do so.
Who knows how many exoplanets are genuinely there in our Milky Way galaxy, which has between 250 and 500 billion stars.
There are more than 700 confirmed multi-planetary systems or stars with at least two planets.
The Kepler-90 planetary system, like our Solar System, has eight planets.
The TRAPPIST-1 planetary system, which has seven planets, is another sizeable planetary system.
Luyten’s Star is the nearest planetary system to our Solar System with more than one planet. It is only 12.20 light-years from Earth and is home to four known exoplanets.
Within our Milky Way galaxy alone, scientists believe that there are at least six billion planets similar to our Earth.