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UY Scuti

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description UY Scuti Overview

UY Scuti is a red supergiant star in the constellation Scutum, classified as a semiregular variable with a pulsation period of approximately 740 days. Located near the center of the Milky Way at an estimated distance of about 5,100 light-years, the star has been identified as one of the largest known stars by radius. Published estimates have placed its radius at approximately 1,700 times that of the Sun, though subsequent studies have suggested this value may be uncertain due to difficulties in measuring such distant stars.

help UY Scuti FAQ

Is UY Scuti still considered the largest known star?

It remains one of the largest known red supergiants, but it cannot be given an uncontested number-one ranking. Revised distance data and the diffuse, pulsating boundaries of supergiants have reduced some modern radius estimates well below the older figure of about 1,700 solar radii.

Would UY Scuti engulf the Solar System if it replaced the Sun?

Even estimates near 900 solar radii would place its visible surface beyond Earth's orbit and near or beyond the asteroid belt. Under the older 1,700-solar-radius estimate, it would extend past Jupiter's orbit.

Can UY Scuti be seen without a telescope?

No. Despite its enormous physical size, UY Scuti is thousands of light-years away and is dimmed by dust, with visible brightness around magnitude 9 or fainter. A telescope and a reliable star chart are needed to identify it in Scutum.

Why do published estimates of UY Scuti's radius vary so much?

Its calculated radius depends on uncertain distance, temperature, brightness, and the wavelength used to define its surface. UY Scuti also pulsates and has an extended atmosphere, so it lacks the sharply defined edge of a solid object.

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