The European Southern Observatory (ESO) has discovered a third Earth-like planet orbiting the star Proxima Centauri, the closest star to our sun at four light years away. A planet is considered Earth-like if scientists suspect it provides conditions that could make life theoretically conceivable, such as a certain temperature range, gravity, an atmosphere and the possibility of water.

Astronomers discovered the planet through the Very Large Telescope (VLT) in Chile's Atacama Desert. Proxima d is the lightest of the three planets discovered around our closest star. ESO researchers also discovered the somewhat larger Proxima b, but with a different telescope supported by the planet-search instrument HARPS.

Many Earth-like planets haven't been discovered by telescopes situated on Earth but by ones in space. Spaceship Kepler has been searching for Earth-like planets since 2009. Besides meeting the physical conditions, they must also consist of rock or metal compounds and have a solid surface, in contrast to gas giants like Jupiter and Saturn.

Exoplanet Kepler-186f is located 500 light years away from us, orbiting red dwarf Kepler-186. That small sun has only about 4% of the energy of our sun. Kepler-186f orbits Kepler-186 at a perfectly calibrated distance: Water would neither freeze nor evaporate on the planet, which is a precondition for life. But the question of whether there is water on Kepler-186f at all remains unanswered.

There are no detailed pictures of exoplanets, just artistic representations like this one of Kepler-186f. But not even a drawing exists of another recently discovered exoplanet, Kepler-438b, which orbits a sun-like star about 470 light years away from Earth and is just slightly larger than our planet. NASA published the discovery on January 6, 2014.

This artist's drawing of Kepler-62e shows a planet covered by ocean. Scientists agree that Earth-like exoplanets most likely have large oceans. Kepler-62e can be found in the constellation of Lyra, located 1,200 light years away from us. And its mother star, Kepler-62, has yet another Earth-like planet ...

... Kepler-62f, whose diameter is 1.4 times that of Earth. The Earth-like planet is located a bit further out in its solar system than its larger brother Kepler-62e, which is 1.61 times as big as Earth. Both may be suited for life. Researchers believe that the existence of rocks and water is plausible.

Even though Kepler-16b is located on the edge of an inhabitable zone, it probably doesn't host any life. This is a pity, because the planet orbits two suns — every morning and evening, its inhabitants would be able to observe two sunrises and sunsets! Too bad Kepler-16b is most likely a gas planet, composed of rock and ice — not good for beings needing to breathe fresh air.

The Pillars of Creation are located in the Eagle Nebula about 7,000 light years away. The joint ESA and NASA Hubble Space Telescope took new pictures of the formation through an infrared light spectrum. The pillars are home to numerous bright and young stars, including entire solar systems.

The same picture through visible light: more fog, but also more color. Dust and gas in the pillars are pierced by radiation originating from young stars. These new Hubble Telescope pictures enable researchers to monitor changes in the formation over a longer period of time.

NGC 4102 is a LINER galaxy: a low-ionization nuclear emission-line region. This means it emits ionized radiation, like roughly one-third of all galaxies. At its center, there is a sun-burst region, where young stars seem to be born. It has a diameter of about 1,000 light years. Scientists don't understand the exact processes in the center yet.

This cluster of stars, located in the northern part of the Hercules formation, is called Messier 92. On dark nights with clear skies, we can see it from Earth with bare eyes. The cloud includes roughly 330,000 stars, most of which consist of hydrogen and helium. Heavier elements like metals are rare.

The original version of this photo of the Andromeda Galaxy is 1.5 billion pixels in size — the most detailed picture ever taken of that galaxy. It includes 100 million stars and thousands of star clusters. To watch it in its entire beauty, one would need 600 HD-TV screens. The ends of the picture are 40,000 light years apart.