If you have ever had a medical checkup, you have probably heard about the Body Mass Index (BMI) that it supposed to have an optimal value around 25. Probably you were told to take your weight in pounds, divide it by the square of your height in inches and multiply the result by 703 to find your BMI.
Well, astronomers think there are large number of stars and guess (estimate) that there are around 1 septillion stars in the Universe1. If you look at the night sky, you can see around 3,000 stars with the naked eye. A galaxy is a group of hundreds of billions of stars that are relatively close to each other.
For the past month or longer, the planets of Venus and Jupiter have frequently been visible in the night sky. Tonight, as with last night), Astronomy Ireland is saying that there will be a particularly beautiful sight as Venus and Jupiter will be spectacularly bright in the western sky alongside a thin crescent Moon.