The upper part of the figure shows the HZ of the Sun (at its present ... The purple bars surrounding planets Gliese 581 c and d illustrate the variable distance to the star caused by the ...

Who determined that the sun was a star, like the stars in the nighttime sky? Mike Curtiss West Richland, Washington No single astronomer had this realization. Prominent thinkers considered the ...

Its host star is in the same class our sun, but slightly smaller and cooler ... The distant orb circles a red dwarf star called Gliese 581 that is located about 20 light-years away from Earth.