The First Magnitude Stars

The First Magnitude Stars Table given below lists the brighest stars in the sky that are -1, 0 and 1 magnitude. Sirius is considered the brighest among all stars and has a magnitude of -1.44. Dimmer stars are given positive numbers. The larger the number means the dimmer the star is. We had previously carried an article about how the Magnitude of Stars is determined.

An Artists conception of Sirius A and B . Image-credit:soldesirius.blogspot.com

Many stars have a negative magnitude. Obviously these would appear even brighter than the first magnitude stars. In all there are about 20 stars of first magnitude or brighter. On clear nights stars of up to magnitude 4 are normally visible in the city sky, but fainter ones (up to magnitude 6) can be seen from the countryside where there is no glare of city lights.

First Magnitude Stars Table

Why  do bright objects in the night sky have negative magnitude and dim objects positive magnitude ?

The concept of Magnitude traces to the Greek astronomer Hipparchus (or the Alexandrian astronomer Ptolemy—references vary). He classed stellar objects on how bright they appeared — the brightest were classified as  “magnitude 1,”  and the next brightest were categorized as “magnitude 2,” and so on down to “magnitude 6,” the faintest that he could see. This scale is roughly more than 2000 years old.

Absolute Magnitude Scale based on Vega

The star Vega is defined to have a magnitude of zero, or at least very close to it. Modern instruments such as bolometers and radiometers have given Vega a brightness of about 0.03 magnitude. The brightest star in the night sky – Sirius, has a magnitude of −1.46. or -1.5.

Related posts:

1. Canis Major – The Great Dog
2. Lyra – The Harp
3. The Night Sky – An Introduction to Astronomy