Red giant
Videos
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature
An illustration comparing the structure of the Sun (left) and its possible future as a red giant (right; not to scale, this image is of a false color for more contrast and does not depict stellar mass loss and the asymmetry of a red giant and the Sun is actually beige-white; an actual red giant would be orange-white to human eyes). The inset at the bottom right shows a size comparison.
This image tracks the life of a Sun-like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years
Mira A is an old star, already shedding its outer layers into space
Sun
Videos
The Sun is the star located at the centre of the Solar System. It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surf
Red giant
…luminosities up to nearly three thousand times that of the Sun (L☉); spectral types of K or M have surface temperatures of 3,000–4,000 K (compared with the Sun's photosphere temperature of nearly 6,000 K) and radii up to about 200 times the Sun (R☉). Stars on the horizontal branch are hotter, with only a small range of…
The Sun as viewed through a clear solar filter
The photosphere is structured by convection cells referred to as granules.
The Sun's transition region taken by Hinode's Solar Optical Telescope
During a total solar eclipse the solar corona can be seen with the naked eye.