Solar radius

Solar radius is a unit of distance used to express the size of stars in astronomy equal to radius of the Sun. The solar radius is usually defined as the radius to the layer in the solar photosphere where the optical depth equals 2/3.:

The solar radius is approximately 695,700 kilometres (432,288 miles), which is about 10 times the average radius of Jupiter, 110 times the radius of the Earth, and 1/215th of an astronomical unit, the distance of Earth from the Sun. It varies slightly from pole to equator due to its rotation, which induces an oblateness of order 10 parts per million. (See 1 gigametre for similar distances.)

The SOHO spacecraft was used to measure the radius of the Sun by timing transits of Mercury across the surface during 2003 and 2006. The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles).

Haberreiter, Schmutz & Kosovichev (2008) determined the radius corresponding to the solar photosphere to be 695,660 ± 140 kilometres (432,263 ± 87 miles). This new value is consistent with helioseismic estimates, and the same study showed that previous estimates using inflection point methods had been overestimated by approximately 300 km.

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Watch wind whirl from the Sun

European Space Agency 26 Mar 2025
Aside from sunlight, the Sun sends out a gusty stream of particles called the solar wind ... Solar Orbiter is on a mission to uncover the origin of the solar wind ... The vertical edge of the video spans 1 274 000 km, or 1.83 solar radii.
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Two new brown dwarfs discovered with TESS

Phys Dot Org 17 Mar 2025
... mass range between 13 and 80 Jupiter masses (0.012 and 0.076 solar masses) ... When it comes to the host TOI-5422, it is a subgiant star with a radius of 1.48 solar radii and a mass of 1.05 solar masses.
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