Two weeks ago I wrote an article about The Scientific Search for Aliens, and this week’s news left me jumping for astrophysics joy. A team of scientists at the Queen Mary University of London has just announced, via publication in Nature, that they have discovered a planet orbiting Proxima Centauri. When the Voyager 1 spacecraft photographed the Earth small and lonely as a “Pale Blue Dot” in 1990, “our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, [was] challenged by this point of pale light” (in the words of Carl Sagan). Now, in the soft red glow of Proxima Centauri, we may have discovered a celestial neighbor like our own—a pale red dot.
Proxima Centauri is a red dwarf star—which means that it is a relatively small, cool star approximately a tenth the size of our sun. Additionally, Proxima Centauri is the closest known star to our sun, approximately 1.3 parsecs away. In 2000, the results from a spectrograph showed that the star’s brightness dimmed a bit every 11.2 days, opening up many possibilities for this occurrence: solar flares, Cepheid variability, or an orbiting planet. The London team further observed the star using instruments in Chile—nearly every night for two months—and have ruled out the other possibilities, leaving the most likely explanation as an orbiting planet with a period of 11.2 days.
While there are over 3,000 exoplanets we’ve discovered, this new planet is very special: according to the team’s leader Guillem Anglada-Escudé, “the search for life starts now”. This planet ticks off so many of the desired traits when looking for a planet to colonize, or looking for a planet that might host alien life. The planet is about 1.3 times the size of the Earth, which means that it is large enough to command a protective atmosphere, yet has weak enough gravity to allow life form like us to exist. Additionally, and most excitingly, this planet exists in the “Goldilocks Zone” where it is close enough to the sun to have liquid water: much closer, and all water would be evaporated, but much further and all water would be frozen.
There are still many questions to answer before we deem this planet entirely habitable, however, and only so many of them can be answered from here on Earth; sending a probe to investigate the planet seems to be a clear next step. The vast distance between star systems has been the main halting factor in space exploration, so thankfully the journey to this planet is feasible by virtue of Centauri’s proximity. Additionally, we could send a probe to this planet in a mere 20 years with the partnership of “Breakthrough Starshot,” a science-entrepreneur team working on the quickest space probes yet. The Starshot project, announced and funded in April 2016, plans to use a solar sail to use the momentum of photons in order to propel a tiny pint sized space probe all the way to the Centauri system. According to the proposal, this ship should be able to travel at 20% the speed of light—an absolutely unprecedented speed, yet use no fuel.
In the words of Carl Sagan, “the surface of the Earth is the shore of the cosmic ocean. Recently we’ve waded a little way out—maybe ankle deep—and the water seems inviting.” So, we’ll raise the sails on this Starshot probe, send her on her way, and wait in anticipation for twenty years. The probe may discover signs of alien life, but we should not hold our breath for such a groundbreaking discovery; instead, we should take all that we learn about this planet and use that knowledge to propel us forward, because whatever the outcome it will advance our knowledge of our celestial neighborhood light-years (or at least 1.3 parsecs). We will keep discovering planets such as this, and we will continue to innovate our spacecraft designs: each mission we accomplish equips us with the further ability to explore the final frontier. This discovery was built upon the work done by astrophysicists such as Sagan, and promises to be the next big step into the cosmic ocean.
