The Cosmic Distance Scale
By Maggie Masetti
This feature will give an impression of how immense our Universe is by employing a method used many times in "Power of 10" films - that is, starting with an image of the Earth and then zooming out towards the furthest visible reaches of our Universe.
This is not, however, an exercise in "powers of 10" - on the contrary, our goal is to show you astronomical distances without scientific notation. We instead focus on the large number of zeros that are in astronomical distances when we measure them with a familiar unit like the kilometer. The number of zeros increase with each zoom, though not at a constant rate.
Why was this feature written? The Imagine the Universe! "Ask An Astrophysicist " service gets many questions asking why humans do not travel to the nearest star or galaxy - many people do not realize how spectacularly far away the "nearest" astronomical objects are.
A note to teachers: This product passed the NASA Education Product review in 2010. For information about Educational Standards that this feature meets, please visit the DLESE catalogue's entry for the Cosmic Distance Scale: http://www.dlese.org/library/catalog_DLESE-000-000-006-009.htm
Here is a unique Solar System distance scale that utilizes sideways scrolling - this is partly to show just how big the Solar System proper is, but also why it's impossible to show the planets to scale on a poster.
Additionally, here are the newest candidates (as of September and May 2015 respectively) for farthest galaxy yet detected. EGS8p7 at more than 13.2 billion light years away, and EGS-zs8-1 at 13.1 billion light years away.
More new candidates for farthest galaxy were added to the info page for the Farthest Visible Reaches of Space (Interesting link of note: This Flash "Scale of the Universe" visualization is really cool. As is this new one produced by the same folks.)
How do I begin?
Simply click below on the link that says "Begin". A page will open with our starting point - Earth. From there, you may zoom out to the next stopping point on our voyage into the depths of outer space by clicking on the "zoom out" link. Every page will give you an opportunity to stop and learn about the objects that are located at that particular distance via a link at the bottom of each page. Each "Tell Me About _____!" page will have information about the image, about the object, how far away it is, what kind of units astronomers use when referring to distances of that magnitude (to avoid using large numbers of zeros!), how distances to that kind of object are determined, why these distances are important to astronomers, and how long it would take for us to travel from Earth to that object. Often external links are employed when they are deemed useful. Click on the word "Back" at the bottom of the page to go back to the Distance Scale. If you wish to zoom back to the Earth, just click on the "zoom in" links.