Here's why:
* The magnitude scale works in reverse: Brighter objects have *smaller* magnitudes.
* The scale is logarithmic: A difference of one magnitude corresponds to a brightness difference of about 2.5 times.
* Zero is roughly the brightness of Vega: This bright star is used as a reference point for apparent magnitudes.
Examples:
* Sirius: The brightest star in our night sky has an apparent magnitude of -1.46.
* Canopus: The second brightest star has an apparent magnitude of -0.72.
* Arcturus: A bright star with an apparent magnitude of -0.04.
So, a star with a magnitude of -5 is significantly brighter than a star with a magnitude of +5.
