Apparent magnitude is a measure of how bright a celestial object appears from Earth. It is a logarithmic scale, meaning that a difference of 5 magnitudes corresponds to a brightness factor of 100. The lower the number, the brighter the object; for example, a star with an apparent magnitude of 1 is much brighter than one with a magnitude of 6. This scale helps astronomers compare the brightness of different objects, such as stars, planets, and galaxies. For instance, the Sirius star has an apparent magnitude of -1.46, making it one of the brightest stars visible in the night sky.