Astronomers Find Earth-Like Planet Just One Star Away

An artist’s impression of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri. Image Credit: ESO/M. Kornmesser

 
The nearest star to Earth (aside from the Sun) might have an Earth of its own, scientists announced today. Proxima b, which orbits the star Proxima Centauri, is a rocky world about our size, mass, and temperature. It orbits within what astronomers call the "habitable zone," and it is able to harbor liquid water on its surface.

In other words, it might be able to support life.

The findings, published today, August 24, in Nature, are the result of work by a research team of more than 30 scientists from around the world who have been documenting their search for just such a planet through the Pale Red Dot campaign (in honor of both Proxima's assumed red hue and the Pale Blue Dot we call home). 

For all the similarities, there are some significant differences between Proxima b and Earth. One year on Proxima b would be 11 Earth days long, and its distance from its host star is less than that of Mercury to the Sun. (Despite being the planet nearest to the Sun, Mercury isn't the boiling cauldron you might expect. It's not even the hottest planet in the solar system—that honor belongs to Venus, whose surface would melt solid lead. Mercury, on the other hand, possesses water ice.) Proxima Centauri is much cooler and smaller than our Sun—it's closer in size to Jupiter—leaving the rocky world of Proxima b suitable for water, atmosphere, and life.

WOBBLY STARS

An exoplanet is a world that orbits a star other than our own. (Scientists have also identified "rogue" exoplanets, which orbit no star at all.) There are more than 3500 identified exoplanets in the universe, orbiting thousands of different stars. Thousands of additional candidate exoplanets have been spotted and await further study before being made official.

Such planets are discovered using several methods. When a planet's orbit places it between its star and Earth, the amount of light we receive from the star is diminished. Dimming over a consistent interval might suggest a planet. Conversely, a planet can sometimes make a star seem brighter, depending on its closeness to the star and the thermal radiation it thus emits. Planets with significant mass have a gravitational pull on stars. We can detect such movements by way of the Doppler effect. Electromagnetic waves produced by a star as it approaches the Earth are of a different frequency than waves produced by a star as it moves away. Shifting frequencies of a star suggest a wobble, and therefore the possible influence of a planet.

It is the latter technique scientists used to find Proxima b. An observed wobble doesn't automatically mean an exoplanet; sunspots can have the same apparent effect. However, research by John Barnes of the Open University in England ruled out sunspots as the cause of Proxima Centauri's oscillations. "Once we had established that the wobble wasn’t caused by star spots, we knew that there must be a planet orbiting within a zone where water could exist, which is really exciting," he said in a press statement.

SECOND STAR TO THE RIGHT

Proxima Centauri is a red dwarf that's much smaller than our Sun—only about one-eighth the mass—and cannot be seen by the naked eye. It has a lower luminosity, though does exhibit occasional, intense flares of brightness. Such activity, combined with other factors, means that the star has a good four trillion years of life left in it. (The universe itself is only 14 billion years old.)

Before you start packing for the journey to visit our neighbor, know that Proxima Centauri is approximately 38.25 trillion kilometers, or about four light-years, from Earth, and it would take us tens of thousands of years to reach it with existing propulsion systems. Still, studying the star and its newly discovered rocky world will be made much easier once the James Webb Space Telescope, the successor to Hubble, launches in 2018 and the European Extremely Large Telescope comes online in Chile in 2024. If subsequent discoveries indicate the presence of a friendly atmosphere, it would be, according to Barnes, "arguably one of the most important scientific discoveries we will ever make."

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ESO, A. Müller et al.
Here's the First Confirmed Image of a Planet Being Born
ESO, A. Müller et al.
ESO, A. Müller et al.

One of the newest landmarks in the observable universe has finally been captured, according to the European Southern Observatory. The image, snapped at its Very Large Telescope (VLT) in Chile, marks the first time a newborn planet has been seen as it forms. 

The image was documented by SPHERE, an instrument at the VLT that's built to identify exoplanets. It shows a planet, dubbed PDS 70b, taking shape in the disc of gas and star dust surrounding the young dwarf star PDS 70. In the past, astronomers have caught glimpses of what may have been new planets forming, but until now it had been impossible to tell whether such images just showed shapes in the dust or the beginnings of true planet formation. The results of the research will be shared in the journal Astronomy & Astrophysics [PDF].

This latest cornograph (an image that blocks the light of a star to make its surroundings visible) depicts the new planet clearly as a bright blob beside the black star. The two bodies may look close in the photo, but PDS 70b is roughly 1.8 billion miles from PDS 70, or the distance of Uranus to the Sun. SPHERE also recorded the planet's brightness at different wavelengths. Based on information gathered from the instrument, a team of scientists led by Miriam Keppler of the Max Planck Institute for Astronomy says that PDS 70b is a gas giant a few times the mass of Jupiter with a surface temperature around 1830°F and a cloudy atmosphere.

Astronomers known that planets form from solar clouds which stars leave behind when they come into a being, but until now, the details surrounding the phenomena have been mysterious. “Keppler’s results give us a new window onto the complex and poorly understood early stages of planetary evolution,” astronomer André Müller said in a press release. “We needed to observe a planet in a young star’s disc to really understand the processes behind planet formation.”

This is just the latest history-making image captured by the ESO's Very Large Telescope. In the last 20 years, it has documented nebulae, light from gravitational waves, and interacting galaxies.

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iStock
Saturn and a Strawberry Moon Will Brighten Night Skies This Week
iStock
iStock

Summer has officially arrived. That means the weather is finally warm enough in parts of the country to lay down a blanket in your backyard and spend the night staring at the sky. This week is especially exciting for stargazers. According to Mashable, Saturn will be visible in the sky beside a "strawberry moon."

One of the first major celestial events of the season takes place Wednesday, June 27. The Earth will fall directly between Saturn and the Sun on Wednesday and a brightly shining Saturn will be visible in the eastern sky after the Sun goes down. The best time to spot the ringed planet is around midnight, and it will appear in the sky for the next several months.

On Wednesday, when Saturn is at its brightest, the sky will present another treat. A full strawberry moon will rise not far from Saturn's spot around 12:53 a.m. EDT that night and accompany the planet as it moves across the sky. The name isn't a reference to the Moon's hue, but to the time of year when it appears: A strawberry moon is the first full moon of summer, and it was once used by farmers to mark the beginning of strawberry picking season.

These two events are just the start of a promising time of year for astronomy fans. Sync your digital planner to this space calendar so you don't miss out on any other big dates, like the partial solar eclipse on August 11.

[h/t Mashable]

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