What is Antares?

About Antares:

• Antares, also known as Alpha Scorpii, is the alpha, or brightest, star in the constellation Scorpius, and the 15th-brightest star in the whole night sky.
• It is a massive red supergiant star. It is 10,000 times brighter than our sun.
• It is one of the largest known stars, 700 times the sun's diameter, large enough to engulf the orbit of Mars if the solar system were centered on it.
• Despite its size, the overall density of Antares is less than one-millionth that of the sun. 
• Antares is also relatively cool as stars go. Its surface temperature is about 6,100 degrees F (3,400 degrees C). That’s in contrast to our sun’s surface temperature of about 10,000 degrees F (5,500 degrees C).
• The star's low temperature accounts for its ruddy color.

What is a Red Supergiant star?

• They are very large stars that are approaching the later stages of their stellar life.
• They have a radius that is several hundred to 1500 times that of the Sun. 
• Though they are great in size, the red color indicates that stars of this type have a relatively low surface temperature.
• They are highly luminous.
• Most red supergiants are variable stars. This means, their degree of brightness changes and fluctuates as seen on Earth.
• Also, these stars are actively losing mass. Nebulae have been seen around them as they expel material.