The universe had a definite beginning, called the Big Bang. It’s ending is more like the “long, slow expansion”. The truth is, the universe is slowly dying as it expands and grows and gradually cools. It will take billions and billions of…
This is one of those questions that has an answer that is quite mind-expanding. Basically, the universe consists of galaxies and the objects they contain: stars, planets, nebulae, black holes and other dense objects. The early universe was largely hydrogen with some…
The universe began some 13.7 billion years ago in an event called the Big Bang. It was not an explosion (as is often depicted in some artwork) but more of a sudden expansion from a tiny pinpoint of matter called a…
The standard space-travel answer to that question puts the “edge of space” at 100 kilometers above Earth’s surface. That boundary is also called the “von Kármán line”, named after the Theodore von Kármán, the Hungarian scientist who figured it out.
LEARNING OBJECTIVES By the end of this section, you will be able to: Venus, Mars, and our own planet Earth form a remarkably diverse triad of worlds. Although all three orbit in roughly the same inner zone around the Sun and all apparently…
LEARNING OBJECTIVES By the end of this section, you will be able to: Of all the planets and moons in the solar system, Mars seems to be the most promising place to look for life, both fossil microbes and (we hope) some…
LEARNING OBJECTIVES By the end of this section, you will be able to: Mars is more interesting to most people than Venus because it is more hospitable. Even from the distance of Earth, we can see surface features on Mars and…
LEARNING OBJECTIVES By the end of this section, you will be able to: The thick atmosphere of Venus produces the high surface temperature and shrouds the surface in a perpetual red twilight. Sunlight does not penetrate directly through the heavy clouds, but…
LEARNING OBJECTIVES By the end of this section, you will be able to: Since Venus has about the same size and composition as Earth, we might expect its geology to be similar. This is partly true, but Venus does not exhibit the…
LEARNING OBJECTIVES By the end of this section, you will be able to: As you might expect from close neighbors, Mars and Venus are among the brightest objects in the night sky. The average distance of Mars from the Sun…