VOA慢速英语:2017年科学故事排行榜

The year 2017 was marked by some rare scientific events and discoveries.

A rare eclipse covers the US

Among the rare events of the year was a total solar eclipse visible across the United States on August 21. It had been 99 years since a similar eclipse took place in the U.S.

Hundreds of thousands of people across the country took time to see the moon partly or completely hide the sun. Many went to places like Carbondale, Illinois, Madras, Oregon and Charleston, South Carolina to see the total eclipse. Cloudy weather spoiled the view in some places, but many others had clear skies.

Many people saw it for themselves using special telescopes and eclipse sunglasses. Some even projected the image of the eclipse through a pinhole cut into a shoe box!

The next total eclipse to cover so much of America will not happen again until 2045.

Is warming climate making storms worse?

Many scientists are concerned that rising world temperatures will cause more dangerous weather events. And the World Meteorological Organization in Geneva says 2017 could be among the three hottest years on record.

Three powerful ocean storms that struck Caribbean islands and the southern United States in 2017 brought more attention to the issue.

Hurricane Harvey caused incredible flooding to the Houston area in the state of Texas. And Hurricanes Irma and Maria left severe damage in Florida, Puerto Rico and the Caribbean.

Climate experts say rising temperatures will make ocean storms—like hurricanes and typhoons—more intense and with higher wind speeds. Rising sea levels could also make ocean storms worse as waves from the sea force water further inland threatening highly populated coastal cities.

In November, the research group Global Carbon Project released a report on climate change. It predicted that the amount of carbon dioxide released into the atmosphere would grow by two percent this year. The increase comes after two years without a rise in the heat-trapping gas.

The National Oceanic and Atmospheric Administration studies climate around the world. It notes that 2016 was the warmest year since 1880 with temperatures .94 degrees Celsius above the average.

Making waves through space and time

Physicist Albert Einstein predicted that gravitational waves exist more than 100 years ago in his General Theory of Relativity. But scientists have struggled to show evidence of them since that time.

Scientists were able to confirm the existence gravitational waves with a rare collision in space this year. The collision of two very dense neutron stars provided scientists with new evidence.

Neutron stars are the small remains of massive stars that have exploded and lost their outer layers. They are also very massive for their small size.

The collision was discovered on August 17 by the Laser Interferometer Gravitational Wave Observatory, or LIGO, in the U.S. and Europe's Virgo observatory.

These observatories use laser beams to detect the presence of the gravitational waves.

Scientists believe they have detected evidence of the waves before from black holes. But these remains from star explosions are so massive that even light cannot escape them. So astronomers cannot see them or show other evidence of their existence.

What was different in this case was that the neutron stars produced lots of radiation that could be seen on Earth. Observatories around the world including NASA's Fermi space telescope confirmed evidence of gamma rays from the collision.

Gamma rays are electromagnetic radiation, a form of light, that scientist believe are released when super massive objects collide—like two neutron stars.

The event made news for another reason. Scientific theories predict that the resulting explosion will create heavy elements like lead and gold, throwing them far out into space.

The discovery could not have come at a better time. In October, Scientists Rainer Weiss, Barry Barish and Kip Thorne were told they had won the 2017 Nobel Prize in Physics.

The men helped designed the laser equipment LIGO used to detect the neutron star collision.

The Nobel committee said their discoveries "ensured that four decades of effort led to gravitational waves finally being observed." Einstein himself, the committee noted, believed the waves could never be measured.

A good reason to believe in UFOs

And, fans of unidentified flying objects, or UFOs, might be glad to know that the United States Defense Department had a secret program to investigate the mysteries.

From 2007 to 2012, the department spent $ 22 million investigating unexplained objects seen in the air, including some reported by military pilots.

The program was started by former Nevada Senator Harry Reid and had support from lawmakers of both parties. However, defense officials say the Advanced Aviation Threat Identification program ended in 2012.

Still, news reports question whether the search for answers about UFOs continues.

A defense department spokesman noted, "The DoD takes seriously all threats and potential threats to our people, our assets, and our mission and takes action whenever credible information is developed."

Reid answered reporters on Twitter this way: "The truth is out there. Seriously."

Those are just a few of the year's stories. Stay with VOA Learning English to learn more about science and technology.

I'm Mario Ritter.

Mario Ritter adapted it for VOA Learning English from earlier reports and other sources. Hai Do was the editor.