Looking back in time
Even the light you see from our own sun represents a measurably long-ago image.
With all that’s happening in the world today, many of us need an escape. Not necessarily an actual physical escape, but just something to take our minds off the bedlam going on overseas.
For lots of folks, watching a little boob tube (or a lot!) can bring relief. May I suggest a time-travel flick? For those of my generation, "Back to the Future" fits the bill nicely. There have been many time-travel movies over the years, which only points to the fact that we are completely obsessed with the whole concept. However, despite wonderful technological advances, it just isn’t possible yet. Or is it?
What if I told you that going back in time is a reality? Would you believe that an ingenious device, developed over 400 years ago and immensely improved upon today, allows us to peer back millions, even billions of years in the past? I am referring to the humble telescope. With such a device, you and I can embark upon a journey into heavenly antiquity. So, how does this work? Well, let’s dive into a little physics. Bear with me — it’s seriously cool!
When star gazing, what are we actually looking at? Light, of course. Light travels insanely fast; 186,282 miles per second (in the vacuum of space), to be exact. To put this in perspective, if we were able to zip around at that speed, we could circumnavigate the earth (at the equator) 7 1/2 times in one second! That’s over 670 million miles per hour.
Now we’re going to get into some really big numbers. Hang in there! When discussing such enormous speed and distances, it’s much easier to talk about a light year-the distance light travels in one year, which is almost 6 trillion miles.
Light from our sun, for instance, which is almost 93 million miles away, takes about 8 minutes to reach earth. That means we are viewing our star as it appeared 8 light minutes ago. (Reminder — never look at the sun directly!) That means that if our delightfully bright orb were to suddenly go dark (don’t worry, it’s not going to happen anytime soon), we wouldn’t even realize it until 8 minutes after the fact.
What if we were totally nuts and could drive our cars to the sun? Traveling at a constant rate of 65 mph without bathroom/lunch/fuel breaks, it would take over 160 years! That’s an awfully long trip with a car full of bratty kids.
How about booking a flight with (imaginary) Solara Airlines? Your ETA would be significantly shortened to “only” 19 years! The speed of light is so fast, it’s incomprehensible.
Now let’s move farther out. Let’s take a look at the Big Dipper, a grouping of seven stars (referred to as an “asterism” by astronomers) found in the constellation Ursa Major, or the Big Bear. Most of us are familiar with this special stellar ensemble. Visible all year round, those seven stars are not all the same distance away from us. Five of them average about 82 light years away, meaning photons hitting your eyes tonight left those stars in about 1940!
At that time, gas was 11 cents per gallon, the average house cost $2,900 and was about 1,100 square feet (compared $269,000 and 2,540 square feet in 2021!). Average wages in 1940 were $950, and a new car cost $850. World War II was well underway with the Battle of Dunkirk (in May) and the German Blitz of London starting in September. A little closer to home, over 150 people perished in the November Armistice Day Blizzard.
Even farther out in space lies Polaris, the North Star, at 433 light years distant. Around the year 1589, Galileo Galilei reportedly performed his famous gravity experiments, dropping objects from Italy’s Leaning Tower of Pisa.
Andromeda, the nearest large spiral galaxy to our own Milky way, is 2.5 million light years away, yet is observable with the unaided eye under dark sky conditions.
Peering back in time millions of years is hard to grasp, but that’s just peanuts to astronomers. Launched Christmas Day last year, the new James Webb Space Telescope, using amazing infrared technology, will be able reach back billions of years ago, to a time when the universe was very young. Stay tuned; it should be fully operational soon, wowing us with tons of fascinating information that could change the way we view our stellar neighborhood forever.
Until next time, take advantage of the next clear night and enjoy your own little trip into the past, no telescope even needed!
Melissa Gerken and her patient husband Pat reside in Zumbrota. She is a self-described bird nerd, astronomer wannabe and lover of all things wild. She enjoys sharing her passion for nature with others.