Oct 26, 2017

Prospecting for gold in the galactic wilderness

Gold nugget. Photo: studiocasper / iStock

The Earth formed over 4 billion years ago with a ready supply of heavy elements like gold and platinum, but the source of those elements has been somewhat of a mystery.

Stars like our sun fuse hydrogen into helium, and at the end of their lives go on to create carbon and oxygen before exhausting themselves. Bigger stars are capable of the intense pressures needed to make silicon, magnesium, nickel and iron before exploding in ferocious supernova detonations that can make even heavier stuff.

What's next: The recent observation of merging neutron stars puts an interesting twist on the game of elements: three Earth masses worth of gold was found in the remnants of that explosion. This means that, like supernovas, these energetic mergers are capable of forming heavy elements. Which process dominates in the universe? We're still not sure.

Go deeper: More on the neutron star collision.

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Updates: George Floyd protests continue past curfews

Protesters on Tuesday evening by the metal fence recently erected outside the White House. Photo: Olivier Douliery/AFP via Getty Images

Protests over the death of George Floyd and other police-related killings of black people continued Tuesday night across the U.S. for the eighth consecutive day — prompting a federal response from the National Guard, Immigration and Customs Enforcement and Customs and Border Protection.

The latest: The Army moved 1,600 soldiers from out of state into D.C. area, the Defense Department confirmed in a statement Tuesday. Protesters were still out en masse for mostly after curfews began in cities including Washington, D.C., New York City, Los Angeles and Portland.

Primary elections test impact of protests, coronavirus on voting

Election official at a polling place at McKinley Technology High School in Washington, D.C. Photo: Drew Angerer/Getty Images

In the midst of a global pandemic and national protests over the death of George Floyd, eight states and the District of Columbia held primary elections on Tuesday.

Why it matters: Joe Biden, the presumptive Democratic nominee, needs to win 425 of the 479 delegates up for grabs in order to officially clinch the nomination. There are a number of key down-ballot races throughout the country as well, including a primary in Iowa that could determine the fate of Rep. Steve King (R-Iowa).

Iowa Rep. Steve King defeated in GOP primary

Rep. Steve King. Photo: Alex Wroblewski/Getty Images

State Sen. Randy Feenstra defeated incumbent Rep. Steve King in Tuesday's Republican primary for Iowa's 4th congressional district, according to the Cook Political Report.

Why it matters: King's history of racist remarks has made him one of the most controversial politicians in the country and a pariah within the Republican Party.