Physics Today Daily Edition
The Kepler space telescope has uncovered a bounty of planets orbiting other stars, but many of those worlds are too distant for in-depth study. Now astronomers have discovered an exoplanet far closer to home—4.22 light-years, to be exact—and it's potentially habitable to boot. Proxima b, reported 24 August in Nature, sits in the liquid-water-friendly habitable zone of the red dwarf Proxima Centauri, the smallest of the three-star Alpha Centauri system and the star nearest to the Sun. From telescope data collected between 2000 and 2008, researchers picked out hints of a signal indicating that the star was wobbling with a velocity of about 1.38 m/s, potentially due to the gravitational tug of an orbiting planet. A dedicated observing run earlier this year by the European Southern Observatory's 3.6 m telescope at La Silla Observatory, Chile, confirmed the planet's presence. The radial velocity measurements reveal that the planet circles the star every 11.2 days, an orbit that puts the planet within Proxima Centauri's habitable zone, and has a mass at least 1.1 times that of Earth's. Although those parameters seem to suggest that Proxima b is both rocky and suitable for life, it's important to note that the planet's diameter, density, and precise mass are unknown. And astronomers are unsure whether life could thrive on red dwarf planets, since they are probably tidally locked and frequently doused in UV and x-ray radiation from stellar flares.
Still, the fact that Earth's nearest stellar neighbor hosts a potentially habitable planet is a discovery worth celebrating. It's a moment astronomers had hoped for ever since the 2012 claim of a planet circling another star in the Alpha Centauri system was thrown in doubt after follow-up observations and analyses. The discovery should also provide a boost for the ambitious interstellar mission Breakthrough Starshot, which aims to launch high-speed miniature probes to the Alpha Centauri system. Although there are many obstacles to overcome for launching such a mission, Proxima b certainly represents an enticing target.
Credit: Digitized Sky Survey 2; Davide De Martin/Mahdi Zamani
Here are the best places to learn more about the discovery:
The Washington Post has a nice roundup that emphasizes the limitations in our knowledge of whether Proxima b qualifies as "Earth-like."
At Scientific American, Lee Billings, author of a book on exoplanets, details the discovery and adds helpful context.
A New York Times visualization illustrates the location and orbit of Proxima b along with the radial velocity signal that led to the planet's discovery.
Astronomer Abel Méndez at the University of Puerto Rico at Arecibo's Planetary Habitability Laboratory writes that by one measure Proxima b is the most similar exoplanet to Earth that we know, but that doesn't mean it's the most suitable for life.
Science News: Proposed 10 years ago, quantum data locking is a method for encrypting information by encoding the entire message, not just the encryption key, in a quantum system. Now Daniel Lum of the University of Rochester in New York and his colleagues have demonstrated the technique for the first time. They defined the state of a photon as their message and then encrypted it by using an equation to scramble the photon's wave function. That ensured the photon would arrive at the intended location on the detector only if the receiver knew the same equation. Although the demonstration is an important step toward secure quantum communication, the technique may not be practical when applied to real-world messages.
Reuters: The $24 billion project to build a nuclear power plant at Hinkley Point in the UK has inspired several companies and government agencies to begin exploring the potential usefulness of small modular reactors (SMRs). Those scaled-down versions of reactors comprise a series of smaller parts, or modules, that can be made in factories, easily transported to a construction site, and assembled in just 6 to 12 months. Many companies envision using multiple SMRs in the place of a single large reactor because they could produce nearly as much electricity at a fraction of the cost. The UK's National Nuclear Laboratory estimates that by 2035, up to 7 GW of electricity—more than twice the planned capacity of the Hinkley Point power plant—could be generated by SMRs.
New Scientist: A blockchain is a method of securing data by encrypting batches of transactions made within a system and linking them into a chain that is then stored on all the computers in a network. It is most commonly used for cryptocurrencies such as bitcoin. Now residents in a community in Australia will use a blockchain to share the electricity they generate from their home solar panels. In the initial test run, 20 households in the community will be equipped with a Raspberry Pi computer system to track their energy use. The system will record transactions as residents sell their extra electricity to each other, though no energy will actually be traded for the first two months. Assuming the test is successful, PowerLedger, the company behind the system, plans to deploy larger networks in Perth and Victoria next year.