Apparent brightness

Definition

Apparent brightness is the measure of how bright a star appears from Earth. It depends on both the star's intrinsic luminosity and its distance from Earth.

5 Must Know Facts For Your Next Test

1. Apparent brightness is measured in units of flux, typically watts per square meter.
2. It follows the inverse square law, meaning that as distance increases, apparent brightness decreases proportionally to the square of the distance.
3. Magnitude scale is used to quantify apparent brightness; lower magnitudes indicate brighter stars.
4. Apparent brightness can be affected by interstellar dust and gas, which absorb and scatter light.
5. It is different from absolute magnitude, which measures intrinsic luminosity independent of distance.

Review Questions

• What units are used to measure apparent brightness?
• How does the inverse square law relate to apparent brightness?
• What is the difference between apparent brightness and absolute magnitude?

Related terms

Luminosity:

The total amount of energy a star emits per second in all directions.

Absolute Magnitude:

A measure of a star's intrinsic brightness as it would be seen at a standard distance of 10 parsecs.

Inverse Square Law:

A principle stating that a specified physical quantity or intensity decreases in proportion to the square of the distance from the source.