Illustration: Aïda Amer/Axios

The early Earth and other rocky planets may have formed quickly and gently, not violently through collapse and collision, as previously thought.

Why it matters: The details of Earth's formation are a long-standing mystery tied to how life may have arisen.

  • Specifics about planet formation are also key as scientists look out to other solar systems with worlds that might be habitable.

What's happening: A study published in Science Advances last week suggests that the proto-Earth may have hosted water before the Moon-forming impact occurred.

  • Other studies from NASA's New Horizons team found that Arrokoth — a world 1 billion miles past Pluto — also seems to have formed gently over time instead of quickly through collisions.

The big picture: Scientists think they have a pretty good understanding of how the giant planets like Jupiter and Saturn formed, but these new studies and years of research before them are forcing scientists to re-examine how rocky worlds like Earth, Mars and Mercury grew.

  • The gas giants likely formed by gobbling up pebbles, quickly becoming the dominant forces in their parts of the solar system.
  • Scientists are now trying to suss out the role this kind of growth may have played in the way that Earth and other small inner solar system worlds grew.

The intrigue: If Earth and other rocky worlds did grow through pebble accretion, it might have implications for when our planet was habitable.

  • "In principle, if we didn't have the Moon-forming impact, life could have formed much earlier on the Earth, probably," Martin Schiller, co-author of the Science Advances study, told Axios.

What's next: Scientists creating models of planetary formation are focusing on building our solar system from the ground up to test the various theories around how the inner planets — Mercury, Venus, Earth and Mars — formed.

  • Even if these rocky planets grew by pebble accretion, it's possible that dozens of protoplanets and asteroids that grew from that process collided in a violent cascade much in the same way that classical models show.
  • However, it's also possible that pebble accretion would have left the early inner solar system with just five objects — early Mercury, Venus, Earth, the Moon and Mars — with only one huge collision between the early Moon and Earth in the early solar system.
  • "It's really fun because we're reinvestigating all of the things that we had taken for granted and modeled in the past," planetary scientist Kevin Walsh told Axios.

Go deeper: A fingerprint of Earth from space

Go deeper

Trump commutes Roger Stone's sentence

Roger Stone arriving at his sentencing hearing on Feb. 20. Photo: Drew Angerer/Getty Images

President Trump on Friday evening commuted the sentence of his longtime associate Roger Stone, according to two senior administration officials. Stone in February was sentenced to 40 months in prison for crimes including obstruction, witness tampering and making false statements to Congress.

Why it matters: The controversial move brings an abrupt end to the possibility of Stone spending time behind bars. He had been scheduled to report to prison on July 14.

Updated 2 hours ago - Health

Which states have set single-day coronavirus records this week

Data: COVID Tracking Project and state health department data compiled by Axios; Map: Danielle Alberti and Naema Ahmed/Axios

13 states this week surpassed records set just last week for their highest number of coronavirus infections in a single day, according to the COVID Tracking Project and state health department data. 16 states in total reported new highs.

The big picture: The United States' alarming rise in coronavirus cases isn't just due to increased testing — particularly where the number of cases has grown fastest over the last month, Axios' Andrew Witherspoon and Caitlin Owens report.

Updated 3 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 6:30 p.m. ET: 12,389,660 — Total deaths: 557,279 — Total recoveries — 6,830,596Map.
  2. U.S.: Total confirmed cases as of 6:30 p.m. ET: 3,169,611 — Total deaths: 133,885 — Total recoveries: 983,185 — Total tested: 38,856,341Map.
  3. Public health: The reality of the coronavirus bites.
  4. Trade: Trump says he's no longer considering phase-two trade deal with China because the pandemic damaged the two countries' relationship.
  5. 🎧 Podcast: Rural America has its own coronavirus problem.