No of stars in universe
Pro Research Analysisby 
Searched over 200M research papers
Estimating the Number of Stars in the Universe
Visible Stars in the Night Sky
The number of stars visible to the naked eye on a clear night is surprisingly modest. It is estimated that only about 5,000 stars can be seen without the aid of telescopes across the entire sky1. This number, while small compared to the total number of stars in the universe, has historically been used to symbolize infinity due to the vastness and mystery of the cosmos.
Total Number of Stars in the Universe
To estimate the total number of stars in the universe, astronomers use various methods, including photometry-based techniques. One such method involves measuring the extragalactic background light and applying the energy conservation law. By assuming that all radiated photons remain within the universe, researchers have estimated the total number of stars to be approximately 6 × 10^222. This immense number underscores the vastness of the universe and the challenges in comprehending its full scale.
Formation of the First Stars
Understanding the formation of the first stars provides insight into the early universe's structure. Simulations show that dark matter initially dominates, leading to the formation of pregalactic objects through gravitational instability. As these objects merge, primordial gas cools and forms dense molecular clouds. Within these clouds, a dense core undergoes rapid contraction, eventually forming a protostar. Interestingly, this process typically results in the formation of a single massive star per pregalactic halo, as radiative feedback from the star inhibits the formation of additional stars in the same region3.
Conclusion
While only a few thousand stars are visible to the naked eye, the total number of stars in the universe is estimated to be around 6 × 10^22. This vast number highlights the enormity of the cosmos and the complexity of star formation processes. Understanding these processes, from the visible stars in our night sky to the formation of the first stars, continues to be a significant focus of astronomical research.
Sources and full results
Most relevant research papers on this topic
Photometry-based estimation of the total number of stars in the Universe.
The total number of stars in the Universe is about 61022, based on energy conservation law and extragalactic background light levels.
The Formation of the First Star in the Universe
At most one massive metal-free star forms per pregalactic halo, with radiation feedback inhibiting star growth and preventing further star formation in the same pregalactic object.
Highly CitedProtostar Formation in the Early Universe
Primeval density fluctuations from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun, which serves as a seed for the subsequent formation of a massive primordial star.
Highly CitedThe star-formation history of the Universe from the stellar populations of nearby galaxies
The peak of star formation was more recent, around five billion years ago, and high-mass galaxies have different histories from low-mass galaxies.
Highly CitedA gamma-ray determination of the Universe’s star formation history
Star formation peaked about 3 billion years after the Big Bang, with gamma rays from distant blazars revealing the history of the Universe over 90% of cosmic time.
Highly CitedProtostellar Feedback Halts the Growth of the First Stars in the Universe
The first stars in the universe may have been less massive than previously thought, potentially explaining the lack of pair-instability supernovae in abundance patterns of metal-poor stars in our galaxy.
Highly CitedThe first stars in the Universe
The first observable star likely formed 30 million years after the big bang, and the first galaxy as massive as our Milky Way likely formed when the Universe was only 400 Myr old.
Highly Cited