Apparent magnitude is a measure of the brightness of a celestial object as seen from Earth. It is expressed in a logarithmic scale, where the brighter the object, the lower the magnitude. The apparent magnitude of an object is influenced by various factors such as its absolute magnitude (intrinsic brightness), distance from Earth, interstellar extinction (absorption of light by dust and gas between the object and Earth), and atmospheric conditions. The Sun has an apparent magnitude of -26.74, making it the brightest object in the sky, while the brightest planet Venus can reach an apparent magnitude of -4.6. Stars have different apparent magnitudes based on their brightness and distance from our planet. The apparent magnitude system was developed by ancient Greek astronomer Hipparchus in the 2nd century BC and is still widely used in astronomy today.