Engineering News

From New Scientist - Latest Headlines:

The Sun may be smaller than we thought, a new study argues. If correct, then other properties of the Sun such as its internal temperature and density may be slightly different than previously calculated. Understanding the Sun's interior is important as it can help scientists make predictions about space weather and answer questions about the solar system. The Sun has no solid surface. Its atmosphere merely gets thinner and more transparent farther from its centre. Instead the Sun's "surface" is defined to be the depth in the Sun's atmosphere where it becomes opaque to light. Scientists measure this by observing the Sun with telescopes and measuring the distance between the centre of the Sun's disc and its "edge" - the place where its brightness suddenly drops off. This gives a radius of 695,990 kilometres, or about 109 times the radius of Earth. A second, completely different way to measure the Sun's size is by using surface gravity waves called f-modes that ripple across the surface of the Sun like water waves on the ocean.

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