2016 was an exciting year for science and space exploration.
Scientists reported earlier this year that Albert Einstein was right: there really are such things as gravitational waves that move through space.
The discovery of a nearby planet has many people wondering if conditions there could be just right to hold life.
Two other planets, Jupiter and Mars, also made the news. And, what is the possibility that “planet nine” really does exist far out in our solar system?
Let's look back on 2016.
Gravitational Waves: Einstein was right!
It took nearly a century, but scientists finally proved Albert Einstein's theory that gravitational waves exist.
The waves were predicted as part of Einstein's General Theory of Relativity. It is the theory of the physical workings of our world and the universe.
The idea was that gravitational waves are like ripples in space, caused by some violent and energetic processes, such as two black holes crashing into each other.
A group of scientists, including ones from the California Institute of Technology and Ligo Scientific Collaboration, confirmed the presence of the waves.
What exactly are gravitational waves? Well, imagine throwing a stone into a lake. When the stone hits the water, it creates ripples in the lake. Spacetime is like the surface of the water. That means gravitational waves are like the ripples moving out from where the stone lands.
Is There an Earth-like Planet Next-Door?
In August 2016, scientists reported the discovery of an Earth-like planet just 4.2 light years away from us. In space terms, that is like having a next-door neighbor. The planet is an exoplanet, meaning one outside our solar system. It is orbiting the star that is closest to Earth, outside of our solar system.
This makes it the closest planet ever found outside our solar system that could support life as we know it.
An international team of astronomers said the exoplanet is orbiting the star “Proxima Centauri.” Scientists named the planet “Proxima b.” It is a little larger than Earth.
Breakthrough Starshot
Space scientists think an unmanned spacecraft might reach Proxima b before the end of the century -- in time for people alive today to see it.
Back in April, before the discovery, an international team launched a project they hope will answer the age-old question of whether or not we are alone in the universe.
The group includes British physicist Stephen Hawking, Russian-born billionaire Yuri Milner and American Mark Zuckerberg, who founded Facebook.
Called Breakthrough Starshot, the project now will work on how to get to Proxima b.
The team is proposing deployment of thousands of very small spacecraft, called StarChips. Each one will be about the size of a postage stamp.
Team members say the spacecraft could reach Proxima b in about 20 years. They say the first step will require about 20 years of research.
Juno to Jupiter
Jupiter is the fifth - and largest -- planet in our solar system. On July 4, 2016, the American space agency's Juno spacecraft entered Jupiter's orbit. Scientists want to find out about the planet's beginnings, structure, atmosphere and magnetosphere.
Juno is busy taking pictures, and collecting data on Jupiter. Scientists also will study its auroras -- the northern and southern lights and the very strong winds on the planet.
The spacecraft was expected to make a total of 37 orbits, or trips, around Jupiter before the mission ends in 2018.
Making the Trip to Mars
Other scientists continue work on getting people to the planet Mars.
In September, American businessman Elon Musk announced plans to build a colony for up to a million people on Mars. He says his company, SpaceX, is building a powerful reusable rocket and spaceship. He wants to get people to the red planet by the early 2020s.
NASA, the American space agency, has its own program for sending astronauts to Mars. It plans to use its own equipment, some of which is still being developed.
NASA officials are hoping to send humans to Mars, the fourth planet from the Sun, in the 2030s.
Is there a Planet Nine?
Scientists say they have found evidence of a ninth planet in the outer edges of our solar system.
Researchers at the California Institute of Technology said this planet travels in a strange “highly elongated orbit in the distant solar system.”
So far, there have not been any direct observations of the mysterious object.
The scientists said it would take this planet 10,000 to 20,000 years just to make one full orbit around the sun. The new planet, called “Planet Nine,” has a mass about 10 times the size of Earth.
Actual confirmation of a ninth planet would be very big news. Maybe that will be one story making science news in 2017.
I'm Anne Ball.
Anne Ball wrote this story for Learning English. George Grow was the editor.
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Words in This Story
spacecraft - n. a vehicle that travels in space
magnetosphere - n. an area of space surrounding an object in space that is dominated by the object's magnetic field
erupt - v. to send out rocks, ash, lava etc in a sudden explosion
elongated - adj. something that is long
mission - n. a task or job that someone is given to do
