Answer:
Achieving 100% accuracy in counting cosmic objects is not feasible due to the vastness and complexity of the universe. However, based on current scientific estimates and observations, here are the approximate numbers for various cosmic entities:
1. **Stars**: There are an estimated 100 billion to 400 billion stars in the Milky Way galaxy alone. Across the observable universe, there are roughly 1 septillion (1,000,000,000,000,000,000,000,000) stars.
2. **Galaxies**: Estimates suggest there are about 2 trillion galaxies in the observable universe.
3. **Black Holes**: There are estimated to be about 100 million stellar-mass black holes in the Milky Way. The observable universe could contain billions of stellar-mass black holes, with each galaxy potentially hosting a supermassive black hole at its center.
4. **Planets**: The Milky Way is estimated to contain over 100 billion planets. Across the observable universe, this number reaches into the quintillions (10^18).
5. **Galaxy Clusters**: The observable universe contains millions of galaxy clusters. Each cluster can contain hundreds to thousands of galaxies.
6. **Galaxy Superclusters**: There are tens of thousands of galaxy superclusters in the observable universe. Our Local Supercluster, known as the Laniakea Supercluster, is one example.
7. **Nebulas**: Nebulae, the clouds of gas and dust in space, are numerous within galaxies. The Milky Way has thousands of known nebulae, and similar numbers can be expected in other galaxies.
Given the current limitations of astronomical observations and technology, these estimates are based on the best available data. The universe is continually being studied, and these numbers may be refined as our understanding grows.
