 
It is hard to visualize just how large a star like Betelgeuse really is. If it were at the center of our own Solar System, its surface would lie beyond the asteroid belt and it would engulf the orbits of Mercury, Venus, Earth, and Mars.At the right you can see the size of Betelgeuse compared to some other giant stars, and the Sun. There are stars bigger than Betelgeuse, such as Antares, and even bigger ones shown in the next diagram (below). 
Given the sizes involved, there is no scale where we could show all these stars in the same diagram. In the diagram at the left, notice Betelgeuse again. On this scale, most of the stars in the previous picture above would be invisible.Betelgeuse and its red colour have been known for millennia. Aboriginal groups in South Australia have shared oral tales of the variable brightness of Betelgeuse for at least 1,000 years. Calculations of Betelgeuse's mass range from between 10 to 20 times that of the Sun. Its distance has been quite difficult to measure; current estimates place it about 500–600 light-years from us. Betelgeuse is considered to be an isolated 'runaway' star, not currently associated with any cluster or star-forming region. Having been ejected from its birthplace in Orion's Belt, this runaway star seems to be moving through interstellar space at a speed of 30 km/s, creating a bow shockwave over four light-years wide. It is also surrounded by an envelope roughly 250 times the size of the star, caused by mass loss from the star itself. Less than 10 million years old, Betelgeuse has evolved rapidly because of its large mass, and is expected to end its evolution with a supernova explosion, most likely within 100,000 years. Starting in October 2019, Betelgeuse began to dim noticeably, and by mid-February 2020 its brightness had dropped by a factor of approximately 3. It then returned to a more normal brightness range. A study using the Hubble Space Telescope suggests that dust around the star was created by a mass ejection, which cast material millions of miles from the star. This cooling material formed the dust that caused the star's dimming. A pulsating variable star, Betelgeuse has always been subject to multiple cycles of increasing and decreasing brightness due to changes in its size and temperature. Astronomers note that its supernova is expected to occur within approximately the next 100,000 years, and so is unlikely to happen any time soon. In 1995, the Hubble Space Telescope's Faint Object Camera captured the first conventional-telescope image of the disk of another star ... Betelgeuse. Nevertheless, its precise diameter has been hard to define for several reasons:
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