Original: Stars range in size from neutron stars , which vary anywhere from 20 to 40 km in diameter , to supergiants like Betelgeuse in the Orion constellation , which has a diameter approximately 650 times larger than the Sun -- about 0.9 billion kilometres .
Simplified: They have a diameter about 1,500 times bigger than the Sun . The star Betelgeuse , in the Orion constellation is a red supergiant star .