Education

The Cosmic Perspective

"The Earth is a very small stage in a vast cosmic arena… Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves…

It has been said that astronomy is a humbling - and I might add - a character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known.”

From "Pale Blue Dot" - Carl Sagan

Resources and Graphics

Our planet is a tiny speck in an immense void of interplanetary space. Our Sun is one of 200 to 400 billion other stars in our Milky Way galaxy. The Milky Way galaxy is one of over 2 trillion galaxies in the visible universe.

The Hubble Ultra Deep Field is an image of a small region of space in the constellation Fornax, approximately one tenth of the angular diameter of a full moon viewed from Earth, and equal to roughly one thirteen-millionth of the total area of the sky. The small patch of sky in which the galaxies reside was chosen because it had a low density of stars in the near-field. It contains an estimated 10,000 galaxies:

Looking at this small area with of thousands and thousands of galaxies, it is amazing to recall that until less than 100 years ago, many astronomers believed that the Milky Way was the only galaxy in the Universe. The possibility of other galaxies had been debated previously, but the matter was not truly settled until Edwin Hubble confirmed that the Great Andromeda Nebula was in fact far too distant to be part of the Milky Way.

The Hubble Ultra Deep Field

"There is a wide, yawning black infinity. In every direction, the extension is endless; the sensation of depth is overwhelming. And the darkness is immortal. Even these stars, which seem so numerous, are as sand, as dust - or less than dust - in the enormity of the space in which there is nothing. For small creatures such as we, the vastness is bearable only through love."

Carl Sagan

The following resources offer a way to help visualize - at least partially - the otherwise impossible-to-grasp immensity of the Universe.

A visual tutorial on the true scale of the Solar System. Of particular note is the speed of light (denoted by the spiked "c" symbol - 186,282 miles per second - 299,792 kilometers per second) , and how long it takes for light to traverse the very short relative distances within the Solar System.

The Earth imaged from Saturn by the Cassini spacecraft:

These video's discuss our home galaxy, the Milky Way:

On the largest scales stars are organized into galaxies, which in turn form galaxy groups, galaxy clusters, superclusters, sheets, walls and filaments, which are separated by immense voids, creating a vast foam-like structure sometimes called the "cosmic web":

The Scale of the Universe
Based on the 1977 short film Powers of Ten, the Cosmic Eye version is a contemporary update:

This scale of the universe video is more complete in going down to the smallest scale known - the Planck length. An informative set of short videos for the curious (including number 98 on the Planck length) can be found at Sixty Symbols.

Besides Sagan's original, and Tyson's remake, of the Cosmos series, one of the best video series on the nature of the Universe is Brian Greene's The Fabric of the Cosmos. Highly recommended!

The Fate of the Universe
The fate of the universe depends on how dark matter and dark energy affect the overall space-time geometry. The age of the Universe is 13.8 billion years. Because the speed of light is finite, we can't see anything that is so far away that light would have taken longer than that from us to reach us. However, due to the expansion of the Universe, these objects are now 46 billion light years away. For what most astrophysicists consider to be the likely versions of dark matter and energy, the Universe will keep expanding forever, with clusters of galaxies getting ever more and more separated. This is true whether the geometry of the Universe is flat, open, or closed.

In this picture showing a closed space-time geometry, the surface of the sphere is meant to represent the whole Universe. The parts that are "grayed out" are outside our observable Universe; the patch at the top that you fully see is the observable Universe. The radius of curvature of this universe is 120 billion light years. Its circumference is 760 billion light years. Remember, though, that this is the minimum size of the Universe given current data. Most astrophysicists suspect that the Universe is really much larger than that, and indeed may well be infinite. Dark matter and dark energy affect both the shape of the Universe and its ultimate fate, but they affect it differently. Exactly what will happen to our Universe may depend on the details of what dark matter and energy really turn out to be...

The James Webb Space Telescope will be the successor to the Hubble Space Telescope, and is part of NASA's Next Generation Space Telescope program, developed in coordination between NASA, the European Space Agency, and the Canadian Space Agency. Its super-sensitive infrared capabilities will allow it to image even farther back into space and time, gathering data which may reveal fundamental knowledge related to dark energy, dark matter, and the evolution of the universe.

The monumental task of detecting gravitational waves - predicted by Albert Einstein - has been achieved, and right in our back yard at the LIGO facility at Hanford, Washington. The principle investigators for this project and discovery were awarded the 2017 Nobel Prize in physics. Below are a couple of video's that explain the astounding feat and how LIGO works.