by Eric Rasmussen
Take a peek at your current house address. Writing 303 St., Denver, CO 80249 might get a person’s mail delivered correctly, but from a cosmic view, it’s wholly incomplete.
A cosmic address for an Earth-based resident would need to include USA, Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea Supercluster, Universe.
Advancing past the first five steps of our address only begins to mark our place in space. The sixth step of our cosmic address reveals our planet as but one in a system we call the Solar System. Here the sun reigns supreme, grasping all objects within its gravitational realm in a tight embrace.
Add one more step to the cosmic address, and we now find ourselves looking toward Earth from 100,000 light years away. And consider this: a light year is the distance light can travel in one year, about 6 trillion miles. From this vantage point, our sun is hardly unique. It’s but an average star of 250 billion that make up our galaxy, the Milky Way.
As we continue to zoom out, from the Milky Way, we now see a structure composed of millions of galaxies in a cosmic grouping that stretches 110 million light years — the Virgo Supercluster.
The graphic at the beginning of the article shows the Virgo Supercluster as seen with telescopes from Earth. While researching this vast tract of space, astronomers noticed some of the galaxies looked like letters. Not to be outdone by Starbucks and its festive holiday cups, they extracted those letter-like images to create this fun graphic to ring in the season.
How many steps can we take in our cosmic address? How far out into space can we see from Earth? Answer: about 47 billion light years.
However strange it seems to have such an abrupt ending, beyond this point we are forever blind, despite any advancements in technology. This physics of this fact not only keeps us from investigating the cosmos that surely stretches past this cosmic horizon, but it may also spell doom for the ‘Happy Holidays’ written in our night sky.
You see, all points in space are expanding away from one another, and space is curved. The farther any two points are, the greater the expansion and the longer the curve. Our universe is accelerating in its expansion, and at the outer reaches this expansion is greater than the speed of light, once thought impossible.
As our observable universe expands, entire galaxies will be pulled beyond this veil and lost from Earth’s sightline forever. One day in the distant future astronomers may look up and see nothing but darkness beyond our Milky Way; no neighboring galaxies, no Happy Holidays.
This physical reality of the cosmos represents another true wonder of science: Neither fact nor an object, the wonder is time itself. And our time, now, is but a pinprick on a continuum.
To us, the night sky may appear eternal and unchanging, but physics shows it, like everything, is fleeting. Let us all look to the heavens this holiday season and be reminded of how lucky we are to live in this moment and experience such exquisite splendor together.
Happy Holidays from the Cosmos!
Eric Rasmussen, BS, M.Ed., obtained his bachelor of science degree at the University of Colorado at Boulder. He majored in ecology and evolutionary biology, and now serves as a Learning Technology Coach at Erie High School and Erie Middle School in the St. Vrain Valley School District, CO.