May 2, 2019

How to tell if an exoplanet is habitable

This composite image shows an exoplanet (the red spot) orbiting the brown dwarf 2M1207. This is the first exoplanet directly imaged. Image: ESO/Chauvin et al.

Figuring out whether a planet is habitable will take more than just understanding its orbit. According to a new study in the journal Science, scientists will also need to study a world’s atmosphere, magnetic field and even geological composition in order to really know if it’s capable of hosting life.

The big picture: Researchers have been hunting for habitable exoplanets using space and ground-based telescopes for years, but assessing whether a world can support life or not is difficult.

What they are looking for:

  • Considerable time is spent focusing on whether a planet is in its star’s “habitable zone” — an orbit in which liquid water can be sustained on the surface — but that alone can’t predict whether life will exist.
  • “To focus the search for extraterrestrial life, scientists must assess which features of Earth are essential to the development and sustenance of life for billions of years and whether the formation of such planets is common,” the study says.

Details: While understanding an exoplanet’s atmosphere is a good way to start a hunt for life, scientists will also need to learn more about a planet’s composition to see if it’s Earth-like.

  • “The heart of habitability lies in the planetary interior,” the study says.
  • If a world’s core is liquid iron like Earth’s, it could produce a sufficiently strong magnetic field to shield its surface from incoming harmful radiation, protecting water and possible life on its surface.

Even plate tectonics have bearing on habitability because the cycling of a planet’s crust helps control its climate, the study notes.

“By having these different variables, we can say this is the most likely — of all the planets that have been found — this one is the most likely to be habitable or to be most Earth-like,” study co-author Anat Shahar of the Carnegie Institution for Science told Axios.

What’s next: Although scientists have discovered thousands of exoplanets so far, very few of them are thought to be potentially habitable. However, as more powerful telescopes come online, researchers should gain a better understanding of what secrets these planets may be hiding.

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U.S. coronavirus updates: Infections number tops 140,000

Data: The Center for Systems Science and Engineering at Johns Hopkins; Map: Andrew Witherspoon/Axios

The novel coronavirus has now infected over 142,000 people in the U.S. — more than any other country in the world, per Johns Hopkins data.

The big picture: COVID-19 had killed over 2,400 people in the U.S. by Sunday night. That's far fewer than in Italy, where over 10,000 people have died — accounting for a third of the global death toll. The number of people who've recovered from the virus in the U.S. exceeded 2,600 Sunday evening.

Go deeperArrowUpdated 14 mins ago - Health

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 9 p.m. ET: 721,584 — Total deaths: 33,958 — Total recoveries: 149,122.
  2. U.S.: Leads the world in cases. Total confirmed cases as of 9 p.m. ET: 142,106 — Total deaths: 2,479 — Total recoveries: 2,686.
  3. Federal government latest: President Trump says his administration will extend its "15 Days to Slow the Spread" guidelines until April 30.
  4. Public health updates: Fauci says 100,000 to 200,000 Americans could die from virus.
  5. State updates: Louisiana governor says state is on track to exceed ventilator capacity by end of this week — Cuomo says Trump's mandatory quarantine comments "panicked" some people into fleeing New York
  6. World updates: Italy on Sunday reports 756 new deaths, bringing its total 10,779. Spain reports almost 840 dead, another new daily record that bring its total to over 6,500.
  7. What should I do? Answers about the virus from Axios expertsWhat to know about social distancingQ&A: Minimizing your coronavirus risk
  8. Other resources: CDC on how to avoid the virus, what to do if you get it.

Subscribe to Mike Allen's Axios AM to follow our coronavirus coverage each morning from your inbox.

World coronavirus updates: Cases surge past 720,000

Data: The Center for Systems Science and Engineering at Johns Hopkins, the CDC, and China's Health Ministry. Note: China numbers are for the mainland only and U.S. numbers include repatriated citizens and confirmed plus presumptive cases from the CDC

There are now more than 720,000 confirmed cases of the coronavirus around the world, according to data from Johns Hopkins. The virus has now killed more than 33,000 people — with Italy alone reporting over 10,000 deaths.

The big picture: Governments around the world have stepped up public health and economic measures to stop the spread of the virus and soften the financial impact. In the U.S., now the site of the largest outbreak in the world, President Trump said Sunday that his administration will extend its "15 Days to Slow the Spread" guidelines until April 30.

Go deeperArrowUpdated 1 hour ago - Health