What is the greenhouse effect? - NASA Science
The greenhouse effect is the process through which heat is trapped near Earth’s surface by substances known as ‘greenhouse gases.’ Imagine these gases as a cozy blanket enveloping our planet, helping to maintain a warmer temperature than it would have otherwise. Greenhouse gases consist of carbon dioxide, methane, ozone, nitrous oxide, chlorofluorocarbons, and …
Black Hole Anatomy - Science@NASA
Anatomy of a Black Hole Event Horizon This is what makes a black hole black. We can think of the event horizon as the black hole’s surface. Inside this boundary, the velocity needed to escape the black hole exceeds the speed of light, which is as …
What Is Climate Change? - NASA Science
Climate change is a long-term change in the average weather patterns that have come to define Earth’s local, regional and global climates. These changes have a broad range of observed effects that are synonymous with the term. Changes observed in Earth’s climate since the mid-20th century are driven by human activities, particularly fossil fuel burning, […]
The Causes of Climate Change - Science@NASA
In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change, composed of scientific experts from countries all over the world, concluded that it is unequivocal that the increase of CO 2, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the ...
Four Forces - Science@NASA
The Four Fundamental Forces Why does Earth stay in orbit around the Sun? How does light travel? What holds atoms and nuclei together? For centuries, scientists have sought to describe the forces that dictate interactions on the largest and smallest scales, from planets to particles. They understand that there are four fundamental forces — gravity, […]
Hubble Skymap - NASA Science
The Hubble Skymap puts the night sky at your fingertips any time of day. Roam the Milky Way to find a selection of galaxies, stars, nebulae and more, and click for a Hubble’s-eye-view of each object. To explore the skymap, scroll, double click, or …
Stars - NASA Science
Astronomers estimate that the universe could contain up to one septillion stars – that’s a one followed by 24 zeros. Our Milky Way alone contains more than 100 billion, including our most well-studied star, the Sun. Stars are giant balls of hot gas – mostly hydrogen, with some helium and small amounts of other elements.
Star Types - Science@NASA
Types of Stars The universe’s stars range in brightness, size, color, and behavior. Some types change into others very quickly, while others stay relatively unchanged over trillions of years. Main Sequence Stars A normal star forms from a clump of dust and gas in a stellar nursery. Over hundreds of thousands of years, the clump […]
Galaxies - NASA Science
Galaxies consist of stars, planets, and vast clouds of gas and dust, all bound together by gravity. The largest contain trillions of stars and can be more than a million light-years across. The smallest can contain a few thousand stars and span just a few hundred light-years. Most large galaxies have supermassive black holes at […]
How Do Planets Form? - NASA Science
When a star is in its forming disk, otherwise known as the T Tauri phase, it is ejecting extremely hot winds dominated by positively charged particles called protons and neutral helium atoms. Although much of the material from the disk is still falling on the star, small groups of lucky dust particles are crashing into one another, clumping into larger objects.