Size and Space
Friday, June 26 2009 @ 03:35 PM EDT
Contributed by: David Gwyn
I received an awesome email today from a great friend who knew I would appreciate the pictures. I thought it would be great to reuse the photos here and share some perspective on our solar system and beyond.The first picture shows us the inner solar system, plus the strange addition of the dwarf planet Pluto. The image gives us a great perspective on why Venus is often called Earth's sister planet, as they are both relatively the same size, with Venus having a diameter 86% of Earth's. Mars weighs in at 53% of Earth's diameter and only about 11% of Earth's mass. Little Mercury follows up behind with roughly 38% of Earth's diameter and only 6% of her mass.
Looking outward, we see the gas giants with Jupiter showing us why it is the biggest planet in the solar system. With a diameter over 11 times the size of Earth, and 318 times her mass. Saturn, the second largest planet in the solar system, has a diameter 9.4 times that of Earth, but because the gas that makes up Saturn is so light, it has only 95 times the mass of Earth. Since we know that Bertha can see Uranus, what does Bertha actually see? Well, Uranus is 4 times the size of Earth. That's a big, ah...planet. What makes it tough to see though is that it's 19 times farther away from the sun than Earth, so that makes the apparent size of Uranus much smaller. (that's a relief, huh?) Moving further out and away from anatomically-oriented space objects, we find the last gas giant, Neptune, at roughly 3.9 times the size of Earth. It's even hard to see is that it's 30 times further away from the sun, or 4.5 billion km away. Putting it all together, the sun certainly makes Earth look like the Little Blue Marble it was called back in the 60's. Little Mercury is a tiny spec compared to our central fire ball. Let's take a look at how our star stacks up against other stars we can see. What makes this picture so interesting is that I was using Arcturus last night to align Bertha, switching between Polaris and Arcturus. As you can see by the picture, Arcturus is about 10 times bigger than our sun but its luminosity is about 100 times greater. One of the closest giant stars, it's 36 light years away and is the fourth brightest star in our night sky. Sirius, or the Dog Star, the brightest star in our night sky, is twice the size of our sun and about 20 times brighter. The reason it is brighter than Arcturus is that it's only about 8.7 light years away.
But Arcturus isn't nearly the biggest thing we can see. Take a look at the right shoulder of Orion and you'll see the red colored Betelgeuse. This star is 1000 times bigger than our sun and 13,000 times brighter. But, it gets even better. Antares is a class M supergiant star, with a diameter of approximately 700 times that of the sun. If it were placed in the center of our solar system, its outer surface would lie between the orbits of Mars and Jupiter. Antares is approximately 520 light years from our solar system. Its visual luminosity is about 10,000 times that of the Sun, but because the star radiates a considerable part of its energy in the infrared part of the spectrum, the bolometric luminosity equals roughly 65,000 times that of the Sun!