In July, 2015, NASA's Kepler mission has confirmed the first near-Earth-size planet in the "habitable zone" around a sun-like star. This discovery and the introduction of 11other new small habitable zone candidate planets mark another milestone in the journey to finding another "Earth"

The newly discovered Kepler-452b is the smallest planet to date discovered orbiting in the habitable zone—the area around à star where liquid water could pool on the surface of an orbiting planet—of a G2-type star, like our sun. The confirmation of Kepler-452b brings the total number of confirmed planets to 1,030.

"On the 20th anniversary year of the discovery that proved other suns' host planets the Kepler has discovered a planet and star which most closely resemble the Earth and our Sun," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate in Washington. “This exciting result brings us one step closer to finding an Earth 2.0.”

Kepler-452b is 60 percent larger in diameter than Earth arid is considered a super-Earth-size planet. While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have-a good chance of being rocky.

While Kepler-452b is larger than Earth, ' its 385-day orbit is only 5 percent longer. The planet is 5 percent farther from its parent star Kepler-452 than the earth is from the sun. Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, has the same temperature, and is 20 percent brighter and has a diameter 10 percent larger.

"We can think of Kepler-452b as an older, bigger cousin to Earth, providing an opportunity to understand and reflect upon Earth's evolving environment," said Jon Jenkins, who led the team that discovered Kepler-452b. "If all the necessary ingredients and conditions for life should exist on this planet, there would be a good opportunity for life to arise."

To help confirm the finding and better determine the properties of the Kepler-452 system, the 'team conducted a series of ground-based observations: These measurements were the key for the researchers to confirm the planetary nature of Kepler-452b and to better pin down(确定)the size of the planet and its orbit.

The future of space exploration may depend on an art form from the past: origami (折纸艺术), the ancient art of paper folding.

Researchers from Washington State University (WSU), US, have used origami to possibly solve the problem of storing and moving fuel to rocket engines, a key challenge in space travel, according to Newswise. They’ve developed a foldable plastic fuel “bladder (囊状物)” resistant to super cold temperatures, which could be used to store and pump fuel in spacecrafts of the future. Their findings have recently been published in the journal Cryogenics.

“Folks have been trying to make bags for rocket fuel for a long time,” said Jake Leachman, one of the lead researchers. “We currently don’t do large, long-duration trips because we can’t store fuel long enough in space.”

Meanwhile, NASA is also looking to paper folding to help observe distant planets. The agency is currently developing Starshade, a foldable, sunflower-shaped piece of hardware that would help block starlight and enable telescopes to view distant objects more clearly in space.

“A huge part of my job is looking at something on paper and asking, ‘Can we fly this?’” Manan Arya, a technologist in California, said. “Once I realized this is how you fold spacecraft structures, I became interested in origami. I realized I was good at it and enjoyed it. Now, I fold constantly. ”

Using origami for space purposes isn’t new, however. Solar arrays (太阳能阵列), experimental wings for space shuttle programs and an inflatable (可充气的) satellite were also inspired by origami in both past and present space projects.

“With most origami, the magic comes from the folding,” Robert Salazar, who helped design the Starshade and now works on the Transformers project, said in a statement. “There are so many patterns to still be explored.”

Except our sun, the lights we see in the sky are all stars light—years from Earth. It’s impossible to know how many stars exist, but astronomers think that in our Milky Way alone, there are about 300 billion.

All normal stars’ birth takes place inside H₂-based gas and dust clouds. Over the course of thousands of years, gravity causes the clouds to shrink until they collapse (坍塌) under their own weight. It is the stars’ first stage of birth. As the clouds get smaller and smaller, they turn around faster and faster, increasing pressure creates rising temperatures inside the gas and dust clouds. And during this time, the stars enter what is known as the relatively brief T-stage that usually lasts millions of years.

When the temperature inside the clouds climbs to about 15 million degrees Celsius, nuclear fusion (核聚变) starts and they enter the next stage of life, known as main sequence. Stars spend 90 percent of their lives in their main sequence phase. Most of the stars, including the sun, are main-sequence stars. They exist in a state of nuclear fusion. This process sends out a huge amount of energy, keeping the star hot and shining brightly. This stage may take billions of years. For example, Earth’s sun is now around 4. 6 billion years old, and it will remain in its main sequence stage for several billion more years.

But there are different ways a star’s life can end, depending on how massive the star is. Less massive stars just burn out. But massive stars die with a Big Bang. While the massive stars may appear to get bigger and bigger on the outside, the matter inside will eventually become so dense (密集的) that they explode. Some of the remains may become neutron (中子) stars or even black holes if they are massive enough.