Can an astronaut see the difference between East and West Berlin ?
Before he returned to Earth from his final space flight on May 14, 2013, Canadian astronaut Chris Hadfield posted photos from the International Space Station (ISS) on his Twitter account. Among them was a photo of Berlin, which showed a clear line of demarcation between the former eastern and western parts of the city. The primary difference was in the street lighting: East Berlin started using sodium-vapor lamps with their yellow glow while it was still a part of the German Democratic Republic (GDR); West Berlin had mostly fluorescent and mercury-vapor lighting, which both produce white light. The difference is still clearly visible— at least to astronauts.
Where is Voyager 1 headed?
Since its launch on September 5, 1977, the space probe Voyager 1 has been steadily exploring our solar system for more than 40 years. In August of 2012 it became the first human-made object to leave our solar system and enter interstellar space. But that was not the end of Voyager’s journey. The space probe continues to fly toward the star Gliese 445, which is 17.6 light-years from Earth and moving toward Voyager 1 and our solar system. By the time the probe reaches the distant star, Gliese 445 will be only 3.4 light-years from us. But don’t get too excited—that will take another 40,000 years.
Can we see distant galaxies with the naked eye?
The Milky Way consists of at least 100 billion stars. If you were to collect all of the euro coins in circulation now, from one-cent pieces to two-euro coins, the total would be close to that number. But it’s actually possible to see even more stars than that with the naked eye—all it takes is the right conditions. If you are in an absolutely dark place on a clear night, such as Cerro Paranal in Chile, and the weather conditions are optimal, you could catch a glimpse of another galaxy too. The Andromeda Galaxy, for example, is 2.5 million light-years from Earth—but thanks to its diameter of 220,000 light-years, it is visible from Earth with the naked eye.
How long would it take to cross the Milky Way?
Our home galaxy, the Milky Way, has a diameter of 100,000 light-years. This staggering figure is equal to 620,000,000,000,000,000 miles or 24,800,000,000,000 times around the Equator. If you wanted to fl y from one end of the galaxy to the other with a modern rocket, the journey would take approximately 100 billion years. By way of comparison: Our universe is only 13.8 billion years old, while our Sun is a relatively young 4.6 billion years—and it’s now about halfway through its life. Scientists estimate it has another 5 billion years or so of activity left in it.