Astronomers have re-calculated the age of our solar system, and found it is very slightly older than we thought – 1.1 million years older, in fact.
That puts our solar system’s age at 4.5684 billion years, rather than 4.5673 billion years. “1.1 million years is a small change,” says Conel Alexander at the Carnegie Institution for Science in Washington, DC. “But it does have important implications for the origin of the early solar system.”
The earliest objects we can date in the system are known as calcium-aluminium-rich inclusions (CAIs), small white flecks millimetres across that are found in meteorites. They are thought to have been the first solids to form out of the nebula of gas that surrounded our young sun.
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żěè¶ĚĘÓƵs can detect certain amounts of elements such as aluminium, calcium and manganese contained within the inclusions. The radioactive decay and amount of these elements can reveal the age of the solar system, with a specific ratio of two types of aluminium called aluminium-26 and aluminium-27 being used to mark “time zero”.
“Not all CAIs formed at exactly the same time, but it looks like more than half formed close” to that time, says Steven Desch at Arizona State University, with the rest forming in a window of about 200,000 years.
There is some debate about whether these elements were evenly spread in the early solar system, which would affect the calculations for when the inclusions formed. Desch and his colleagues reanalysed data on existing meteorites, assuming that they were evenly distributed. The ages of the different elements matched up – supporting the idea that this is correct – and giving a slightly older age than previous studies.
If elements weren’t evenly spread, as various models predict, some unknown process would have been needed to influence the solar nebula, such as powerful solar flares erupting from the sun or a nearby supernova injecting material into the nebula. “The implication [of the new findings] is huge,” says Desch. “You don’t need to invoke flares and supernova injection. This is just what the sun was born with.”
If correct, the new analysis would point to a simpler understanding of how the solar system formed, says Alexander, who wasn’t involved in the study. “In this case, it seems to suggest that the standard picture is probably more or less correct. If things were not uniform, that dramatically changes our picture, which would be very unsettling,” he says.
Icarus
