The universe is expanding, but scientists discovered that its expansion is not slowing down. It is accelerating. So how do scientists know dark energy exists if they cannot see it? The answer comes from measuring how the universe has expanded over time. Distant supernovae, observations of the cosmic microwave background, and measurements of large-scale cosmic […]
How Do Scientists Know Dark Energy Exists? Read Post »
What Happens If You Fall Into a Black Hole? Imagine falling toward a black hole. At first, nothing dramatic happens. As you get closer, however, gravity becomes stronger and spacetime becomes increasingly distorted. Light bends around the black hole, distant objects appear warped, and the difference in gravity between your head and feet begins to
What Happens If You Fall Into a Black Hole? Read Post »
Light travels through space at about 300,000 kilometres per second. Yet once light crosses the boundary of a black hole, it cannot return to the outside universe. Why? The simple answer is not that a black hole “pulls” light backward. According to Einstein’s general relativity, a black hole curves spacetime so strongly that, inside its
Why Can’t Light Escape a Black Hole? The Science Behind the Event Horizon Read Post »
Black holes are formed when matter collapses under gravity so strongly that the collapse cannot be stopped. One of the clearest ways this happens is through the death of a massive star. The process begins inside the star. For most of its life, nuclear fusion produces energy and pressure that support the star against its
How Are Black Holes Formed? From Massive Stars to Cosmic Giants Read Post »
If you have ever wondered what is a black hole, the basic answer is simpler than it first appears. A black hole is a region of spacetime where gravity is so strong that, beyond a boundary called the event horizon, nothing can escape to the outside—not even light. Despite the name, a black hole is
What Is a Black Hole? A Simple Explanation of These Cosmic Objects Read Post »
The Milky Way did not appear as a finished spiral galaxy. It was assembled over billions of years as gravity gathered matter, gas formed stars, and smaller galaxies and stellar systems became part of a growing galaxy. So, how did the Milky Way form? Astronomers think its history began more than 13 billion years ago,
How Did the Milky Way Form? The Story of Our Galaxy Read Post »
The first galaxies did not appear as finished collections of stars. They grew from small differences in the distribution of matter in the young universe. Gravity gradually amplified those differences, dark matter gathered into increasingly massive halos, gas fell into them, and stars began to form inside these growing structures. That is the basic story
How Did the First Galaxies Form? A Journey Into the Early Universe Read Post »
Stars are not all alike. Some are small and relatively cool, while others are enormous, hot and short-lived. The stars we see today also contain elements such as carbon, oxygen and iron that were made by earlier generations of stars. The first stars formed under very different conditions. They appeared during the universe’s early history,
What Were the First Stars Like? How Different Were They From Today’s Stars? Read Post »
Before there were stars, the universe was a very different place. There were no galaxies shining across the sky, no planets orbiting suns, and no familiar starlight. The young universe was filled mainly with hydrogen and helium gas, along with dark matter and radiation. Over time, gravity pulled matter into denser regions, allowing some clouds
The First Stars: How Did They Form in the Early Universe? Read Post »