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.
Well, Sirius is the brightest star in the night sky, so what you see cannot be a star. You are looking at Venus. Venus is the third brightest object in the sky behind the sun and the moon. Venus is visible in the west just after sunset right now. If you still don't believe me, confirm it by downloading this interactive sky chart.