- The Sun’s rotation rate in its first billion years is unknown.
- Yet, this spin rate affected solar eruptions, influencing the evolution of life.
- A team of NASA scientists think they’ve figured it out by using the Moon as critical evidence.
Credits: NASA Goddard/Ernie Wright
Apollo samples and lunar meteorites are a great starting point for probing the early solar system, but they are only small pieces in a large and mysterious puzzle. The samples are from a small region near the lunar equator, and scientists can’t tell with complete certainty where on the Moon the meteorites came from, which makes it hard to place them into geological context.
Since the South Pole is home to the permanently shadowed craters where we expect to find the best-preserved material on the Moon, including frozen water, NASA is aiming to send a human expedition to the region by 2024.
If astronauts can get samples of lunar soil from the Moon’s southernmost region, it could offer more physical evidence of the baby Sun’s rotation rate, said Airapetian, who suspects that solar particles would have been deflected by the Moon’s erstwhile magnetic field 4 billion years ago and deposited at the poles: “So you would expect — though we’ve never looked at it — that the chemistry of that part of the Moon, the one exposed to the young Sun, would be much more altered than the equatorial regions. So there’s a lot of science to be done there."
Banner image: An animated .gif created from images of the Sun taken by NASA's Solar Dynamics Observatory, which observes the Sun 24/7. This image shows the Sun in a wavelength (171 angstrom) of ultraviolet light.