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The Oldest Piece of Earth’s Crust Dates to 4.4 Billion Years Old

The best resource in book form I have found that discusses how the age of the Earth is known is The Age of the Earth by Brent Dalrymple. It is a bit of a dry read but packed with info. There are also good summaries at Talk Origins the first being by Dalrymple himself.

It sounds like they used the Uranium-Lead concordia method (also described here), which takes advantage of the fact that there are two different ways Uranium decays into lead. One from U-238 to Pb-206 and another from U-235 to Pb-207. It is a particularly useful test because zircon doesn’t incorporate lead into its crystal at the time it forms.

Source: Oldest Rock Speck Zeros In On Earth’s Cooling Date

The oldest remaining grain of early Earth’s original solid rock crust has now been confirmed to be a 4.374-billion-year-old old zircon crystal from Jack Hills, Australia.

That age should settle a scientific debate over the accuracy of that mineral’s internal clock, and cuts the time from when Earth was hit by a Mars-sized body (which led to the formation of the Moon) and the cooling and creation of Earth’s first solid crust from 600 million years to 100 million years.

The age of a grain is figured by measuring the amounts of the parent uranium isotopes compared to the daughter lead isotopes.

Cosmos: A Space-Time Odyssey to be Available in Half a Billion Homes

I’m psyched. No pressure Mr. Tyson.

Source: Cosmos: A Space-Time Odyssey

Fox Networks Group (FNG) announced today that COSMOS: A SPACETIME ODYSSEY will debut simultaneously across multiple U.S. Fox networks, including Fox Broadcasting Company (FOX), National Geographic Channel, FX, FXX, FXM, FOX Sports 1, FOX Sports 2, Nat Geo Wild, Nat Geo Mundo and FOX Life on Sunday, March 9 (9:00-10:00 PM ET/PT). This first multi-network launch event for Fox Networks Group, along with the series debut on Fox International Channels and National Geographic Channels International, will make COSMOS: A SPACETIME ODYSSEY available on 220 channels in 181 countries, with an overall footprint of more than half a billion homes.

After the cross-network premiere event, COSMOS: A SPACETIME ODYSSEY will continue its epic 13-episode run, airing Sundays (9:00-10:00 PM ET/PT) on FOX, and Mondays – with all-new bonus footage and behind-the-scenes content – on the National Geographic Channel (NGC) (10:00-11:00 PM ET/PT).