Pale Blue Dot

Comments

Post a Comment

Popular posts from this blog

Your DNA would reach the moon

Image
Foolishness! Your DNA would actually stretch to the sun and back about 4 times! DNA is a fine, spirally coiled thread in the nucleus of every living cell that serves as a guidebook so the cells "know" what they're supposed to do. The strands are so fine you need a high power electron microscopes to see them. The human genome , the genetic code in each human cell, contains 23 DNA molecules each containing from 500 thousand to 2.5 million nucleotide pairs. DNA molecules of this size are 1.7 to 8.5 cm long when uncoiled, or about 5 cm on average. You have about 10 trillion cells in your body , so if you stretched the DNA in all the cells out, end to end, they'd stretch over 744 million miles. The moon is only about 250,000 miles away, so all your DNA would stretch to the moon and back alomst 1500 times. The sun is 93,000,000 miles away, so your DNA would reach there and back about 4 times! Interestingly, no more than 1.5 percent of the human genome contains DN
Read more

What's Outside The Universe?

Image
Bailey, When we were in Albuquerque you asked me what was beyond the edge of the Universe, and I didn't have a very good answer. To be honest, I felt like a baseball player that had practiced and practiced (I've read a lot of books and thought a lot about the same question myself), but suddenly I was standing in the outfield and a high fly ball was headed my way (your question)...and I dropped the ball. Your question is a really good one and a very hard one to answer because the ideas aren't simple and they aren't easy to understand--even for me. But I've been thinking about what you asked, and I'm really, really glad you did becuase it made me think hard about the question again too. Next time we see each other, maybe we can talk about this more, but here's my answer: think about the earth. It's a big ball, and when you look toward the horizon it looks like you can see where the earth stops. But you know from driving and flying that there's no edge.
Read more

Earth's curve tilts bridges

Image
Really. The top of towers of the Verrazano - Narrows Bridge at the mouth of the Hudson river in New York City are tilted almost two inches further apart than the base thanks to the curve of the Earth's surface. Actually, there are a lot of amazing things about that not-so-famous bridge. When it opened in 1964, at 4260 feet it was the longest suspension bridge in the world, exceeding the Golden gate completed in 1937, by 60 feet. Today it's the longest single span in North America and the seventh longest in the world. (The longest is the 6,529 foot Akashi-Kaikyo Bridge in Japan, completed in 1998.) The Verrazano - Narrows Bridge contains enough concrete to construct a single lane highway from New York to Washington, and if the wires that make up the suspension cables were laid end-to-end they would reach 143,000 miles, more than halfway to the moon. On hot days, the double-decker road bed expands almost six feet and sags 12 feet lower, something that ships passing underne
Read more