With concerns growing over the Delta variant of Covid-19, here's what you need to know about whether you need to start wearing a facemask in public again. MSNBC's Brian Williams talks with Dr. Nahid Bhadelia.

"It is called a supermoon because this is a very noticeable alignment," Dr. James Garvin, chief scientist at NASA's Goddard Space Flight Center, said in a statement accompanying a new video on the topic. "The 'super' in supermoon is really just the appearance of being closer."

For the best view, ...

Altocumulus Standing Lenticular Clouds: When sufficient moisture is present above mountain-top level, ACSL clouds develop within the crest of these mountain waves where the air is rising. ACSL clouds are continually developing and dissipating in the vicinity of the wave's crest and immediately dow...

This time lapse footage of the earth during sunrise accross te planet was taken by the International Space Station on October 3, 2015. NASA, 2015

President Obama delivers remarks at COP21 in Paris on the global community's need to address the threat of climate change. November 30, 2015.

2050 is only a short 34 years away. For centuries people have predicted that the future will be taken over by robust robots. But what will 2050 really look like?
10. The world’s population will increase from 7.2 billion to at least 9.6 billion
9. Minorities will reach 50% of the US population -

This video zooms into the core of a rich star-birth region called the Lagoon Nebula, located in the constellation Sagittarius in the direction of our Milky Way galaxy’s central bulge.

When Wylie Overstreet set up his telescope outside on a whim, he had no idea he would inspire awe in hundreds of strangers on the streets of Los Angeles, reminding them of their common humanity.

The modern mammal metropolis of Zootopia is a city like no other. Comprised of habitat neighborhoods like ritzy Sahara Square and frigid Tundratown, it’s a melting pot where animals from every environment live together—a place where no matter what you are, from the biggest elephant to the smallest s

The first free flight of a Morpheus prototype lander was conducted Dec. 10, 2013, at Kennedy Space Center's Shuttle Landing Facility. The 54-second test began with the Morpheus lander launching from the ground over a flame trench and ascending approximately 50 feet, then hovering for about 15 second...