Category Archives: astronomy

The Equinox is Upon Us!

Today, March 19, 2020, is the March equinox. Calendrically speaking, it’s the first day of spring in the northern hemisphere and the first day of autumn in the southern hemisphere. So, happy new season, wherever you are hunkering down during the world-wide pandemic of COVID-19. If you can, step outside for some fresh air and wave to your neighbors (distantly) and enjoy the new season!

The Equinox, Solstice, and our Calendar

Solstices and equinoxes are calendar dates actually related to astronomy and the motions of our planet. Most people think of them as the “start” of a season. They aren’t weather predictions, but are related to positions of the Sun as seen from Earth’s surface. It appears to move, but it’s actually a result of Earth spinning on its axis.

Think of a merry-go-round. If you’re on it and look out at people standing around watching it spin they appear to move. But, they’re really standing still. It’s YOU (and the merry-go-round) that is moving.

It’s the same with Earth. As the planet spins around on its axis, we see the Sun appear to rise in the east and set in the west. Same thing with the Moon and stars. They look like they’re moving across the sky. That apparent motion is at the heart of why we calculate equinox and solstice dates. (Solstices happen in December and June.)

Understanding the Solstice and Equinox

Watch the sunrise and sunset each day (and remember: don’t directly at the Sun). If you do this for a while, you’ll notice that its rise and set points change throughout the year. The Sun also seems to move farther north or farther south through the year. Its sunrise, sunset, and zenith points slide slowly to the north from December 21-22 to June 20-21 each year. After that, they almost stop (or stand still) before stopping. Then, the Sun appears to pause for a day or two before starting the slow daily slide toward the south. That southward trip goes from June 20-21st (the northernmost point) to December 21-22 (the southernmost point).

Solstice sunset in the Rockies. An equinox sunset would be due west.
A winter sunset, where the Sun is very far south along the horizon. On the equinox, the sunset occurs due west. Copyright Carolyn Collins Petersen

Those “stopping points” are called the “solstices” (from the Latin word sol, which means “sun”, and sistere, which means “stand still”). These terms are a heritage from our ancient ancestors. They had an incomplete understanding of Earth’s motions in space but did notice that the Sun appeared to stand still at its northernmost and southernmost points, before resuming its apparent motion south and north (respectively).

Solstice Facts

The summer solstice is the longest day of the year for each hemisphere. For northern hemisphere observers, the June solstice (the 20th or 21st), marks the beginning of summer. In the southern hemisphere, that’s the shortest day of the year and marks the beginning of winter.

Then, six months go by. On December 21st or 22nd, winter begins with the shortest day of the year for the northern hemisphere people. The lucky folks south of the equator get to enjoy the start of summer the same day, with the longest day of their year.

Equinoxes

The word “equinox” also has Latin roots. It comes from aequus (equal) and nox (night). Early observers noticed that the Sun rises and sets exactly due east and due west on the equinoxes. It also appears to cross the celestial equator, a projection of Earth’s equator out to the sky. In addition, day and night are approximately the same lengths.

A shot from the International Space Station of the setting Sun on the June equinox in 2008. Courtesy NASA.

In the northern hemisphere, the March equinox denotes spring and autumn in the southern hemisphere. The September equinox is the first day of fall in the north and the first day of spring in the south.

So, the solstices and equinoxes are important calendar points that come to us from the apparent position of the Sun in our sky. They are also intimately connected to the seasons but are not the sole reason why we have seasons.

Observing the Solstices and Equinoxes

While you can’t “see” the equinox or solstice actually happen, you can chart the motions of the Sun to see how it was that the ancients first came up with these ideas. Take a moment each day to observe the sky. Make a note of where sunset or sunrise takes place along the horizon. Check out your chart against the calendar to see how close they line up.

This is actually a great long-term science activity and I know that it’s a perennial favorite for science fairs. A couple of years ago, I actually went out each night at sunset and got a picture of the sunset using my smartphone. That’s certainly an easy way to do it, and lets you document how the Sun appears to wander north and south along the western horizon.

The Music behind a Science Writer

I’m veering off from pure science writing for a bit to wander over to the arts today. Specifically, music. No, not the physics of music, although that’s a fascinating subject, too. This one’s more about how music weaves itself into my work in certain ways.

As a science writer, I have been inspired by many other people: my dad and mom, Dr. Carl Sagan, my spouse, my graduate school advisor, and certain science writer friends. The one unifying trait they all have (and had) is an unwavering interest in telling the story of science. As a writer, I do the same. I pick apart a subject and analyze it until I understand it. Then, I put it back together in a way that’s useful to my readers. It’s the way I attacked science problems back when I was in grad school and in research. And, it’s a habit that works well for me today.

Weaving Music into the Science Writing Experience

Music is also an inspiration for me. It takes me places as I write. Lately, I realized I do the same thing with music that I do with a science topic. Every once in awhile I’ll be doing something and hear a soundtrack in my head to accompany what I’m doing. It’s not the same as an earworm since those have a half-life that sometimes seems like it’s approaching infinity. No, it’s more like a … well, a soundtrack to whatever I’m doing. Like a visit to my own internal Disney park. And yes, each Disney park has soundtracks.

What does this have to do with science writing? For me, music is part of my writing. Nearly every piece of work I write has a musical backdrop. Thanks to clever composers and performers, my job as a writer is rich and enjoyable.

Music in Concert with Storytelling

Earlier this year, I attended a concert in Denver with Mark to hear the Alan Parsons Live Project perform. Over the years, at our house, we have gotten every album done by Parsons and his talented musical teams. Mark and I are both fans. Mark is a long-time composer of space music and a performer of everything from classical to rock and jazz. He very likely appreciates the Parsons work on a very different level than I do. Mark once arranged and performed I Robot in a concert where Isaac Asimov was in attendance. He talked about that experience in a recent blog entry of his own. The cool thing is, Mark got to share a CD of that concert with Alan Parsons at a “Meet and Greet” event before the Denver concert.

As it turns out, Alan Parsons’ work is part of that music backdrop that underlies my work. That is, of course, when I’m not listening to Mark’s space music, put out under the Geodesium name. He started doing space music for planetarium shows in the 1970s, about the same time as Parsons did his first albums.

They’ve had somewhat parallel careers, albeit Parsons having the bigger name and outreach. But, they were both studio engineers for a time and have headed up record labels. And, they create memorable music. That memorability strikes a chord (see what I did there?) in my brain as I write, and takes me to very different places. Which is useful when I’m writing about distant worlds, stars, galaxies, and the larger universe. It’s very nice to have an in-house space music composer. Over the years, Mark and I have produced a bunch of shows (and his albums) featuring his space music.

Science Writing to Musical Accompaniment

Back when I was first writing about science, I usually clamped headphones onto my head. They were connected to my Walkman. The music I chose helped take me out there to Saturn or Mars or the Milky Way, or wherever. It removed me from Earthly concerns. That way, I could concentrate on those other places I was writing about in my articles, books, and shows.

Of course, I also appreciate music on its own. I don’t HAVE to be working when I listen. And, that’s where the beauty of hearing a live concert comes into play. Then, I can focus on live performance aspects. In the case of the Alan Parsons Live Project concert, I knew most of the music very well. That meant I could analyze it at a different level than when I’m working and listening. Not necessarily harmonically, although that’s part of it. (I did study music back in my first undergraduate career and learned about theory, harmony, and the structure of music.)

Here’s another example of concentration analysis (as I think of it). Mark did a series of pieces designed for exercise (yeah, space music for exercise—it really works!). When I use it during exercise, I analyze the beats, the instrumentation, the melodies, and how it all works together. And, I exercise to the beat. It’s a full-body and full0-mind engagement. Same with some of the Alan Parsons music (some of which I have in my exercise playlist along with Mark’s). Both composers make music that is very harmonically rich and clever, and they engineer their pieces with great ingenuity. And, those are what I focus on when I’m listening intently.

Discovering the Universe using Telescopes… with Musical Accompaniment

As I was sitting there in the concert listening to the Live project band, I remembered listening to various pieces of theirs (and Marks!) when writing my most recent book, The Discovery of the Universe. Nearly every chapter had its own “soundtrack” running on my computer sound system as I worked on it.

For example, when I roughed out the first chapter, I had a mix of APP and GEODESIUM in the playlist. I listened to I Robot when I was writing about robotically controlled observatories later in the book. Mark’s music inspired descriptions of space telescopes and the objects they’ve observed. And, so it went. As I worked my way through a history of observatories and their exploration of the universe, my own inner cosmos reverberated with music.

Music and Science

I’m sure all these thoughts aren’t new to the musically inclined, whether we play, listen, or both. How many of us have “road tapes” (well, today, they’d be “road playlists” on our smartphones or personal music players)? Or, romantic playlists, or work playlists? For people who appreciate music, it’s a way of enhancing our lives. Often enough, it’s a way of simply sitting back and appreciating someone else’s creative genius.

Music Works!

In physics, we learned about sound. I did get interested in the physics of music to understand how and why music sounds the way they do. And, as most of us know who listen to music regularly, music has great affective powers. Musicians know this intuitively, as do composers and sound engineers.

Mark is often asked to comment on his compositions. He points out why he chose certain sounds for certain scenes in the shows we have done. And, he’s turned planetarium show music into a great art form that helps educate people about astronomy. I’m pretty sure you could talk to other soundtrack composers who have similar stories. John Williams, for example, who could tell you just why he chose certain themes for the Star Wars characters. That’s another interesting facet of the way music weaves itself into our lives.

Music of Our Lives

Next time you listen to music, think about what it means to you. How it works in your life. It’s more than just sound waves hitting the bits and pieces of your ears. There are ideas intertwined in those notes, along with experiences, thoughts, and dreams. Together, they become part of the soundtrack of life.