Cosmic flight plans

As we look out at the night sky, one of the greatest challenges is seeing it properly in three dimensions. We are offered the illusion of depth perception by believing that the brightest objects are closer than fainter ones. This is often true; but more often it is not. For example:

Celbalrai is the second-brightest star in the constellation Ophiuchus. (‘Celbalrai’ is Arabic for “shepherd dog.” The names of the stars are Arabic because the Arabs were the preeminent Western astronomers during the Dark Ages. They are credited with preserving the knowledge of the ancient Greek and Roman astronomers through those dark times. It is through their graces that the constellations still retain their Greek names.) Celbalrai stands out to the naked eye at a distance of 82 light-years. Yet, less than four degrees to the left is a star that is only six light-years away! Barnard’s Star is so dim that it requires a telescope to see. It is the second-closest star to our Solar System (after the Alpha Centauri System). It is a very low mass red dwarf star, making it difficult to discover. Indeed, there may be other red dwarfs lurking even closer that are yet to be found.

Thus, as with many things in life, all is not as it seems! We cannot trust brightness as a sole guide to distance in space. We have to dig deeper.

Fortunately, that’s no longer difficult. I can enter the name (or designation) of just about any celestial feature into an Internet search engine and quickly find out how far away it is. What astonishing power this is! Until recently, I had to rely on an old (and very expensive) book that gave crude approximate distances for only a handful of the closest well-known objects.

The challenge now is to find a way to wrap our minds around this new plethora of knowledge. What a waste of a human mind to look up into the sky only see a flat two-dimensional sphere with points of light. I’ve found a fun way to perceive the Universe in three-dimensions by creating interstellar flight plans!

Before pilots set out on a cross-country flight, we put together a flight plan that lists the checkpoints along the route. We measure the distances between them, check the weather and factor in the winds to compute the proper headings and fuel burns. This allows proper weight and balance calculations, ground speed and time en route, etc. (Actually, this is a navigation log, which is only part of a complete flight plan; but we’ll let that slide.) We’re going to take just the first steps of this process to give us a much better feel for our place in the galaxy.

First, check your physics book at the hanger door, and let that little boy or girl out of his/her closet. The speed of light is no problem for us. We’re going to do the impossible in pursuit of knowledge, wonder and fun!

Your orders, Captain Fantastic, are to take your fantastically equipped space cruiser, Starship Fantastic, to Messier Object #4 (M4). Your mission: To seek out new life and new civilizations, of course! Also, stop along the way at targets of opportunity to expand our knowledge.

A bit about our objective: M4 is the closest (confirmed) globular cluster. These clusters are huge balls containing tens of thousands of stars. There are between 150 and 200 of these clusters swarming around the galaxy the way bees swarm around a hive. The current thinking is that these are the remnant cores of small galaxies that were captured by the Milky Way’s gravity and subsequently torn apart by tidal forces. You and your crew will be the first to take in the view from inside a globular cluster!

First, you’ll take the Space Elevator to high Earth orbit where you’ll catch a shuttle to Luna Port. (Each time I mention a new place, you’ll want to check it out with your telescope.) There you’ll pick up your first officer who will be waiting with Starship Fantastic completely fueled and ready in all respects.

You won’t want to go traipsing across the galaxy without your significant other! We’re going to stop at Saturn to pick him/her up, where he/she’s been searching for life in Titan’s ethane lakes. (Saturn is currently in the constellation Scorpius, the Scorpion, as are all of the targets in this flight plan. Titan can be spotted with medium-sized amateur scopes under a dark sky.)

Now it’s time to head out of the Solar System. Let’s take a look at our flight plan (see Figure 1). Our first stop will be the massive star Antares, the brightest star in Scorpius. It’s a red supergiant that’s so large that all of the terrestrial planets (Mercury, Venus, Earth, & Mars) could orbit within it! It has a companion star, called Antares B, that’s 170 times brighter than our sun. Yet, Antares A is so bright (because of its size) that splitting the two with a telescope is very difficult.

The Antares System is about 550 light-years away. That means that at the speed of light, it will take us 550 years to get there. Fortunately, our ship can travel at the speed of thought!

I encourage you to reflect often on the fact that the photons that travel through your telescope, into your eye, and impress an image into your mind have been traveling for 550 years. Those photons cannot be shared (without photography); they belong to you and you alone. That’s a fascinating kind of intimacy. They’re also a time machine, for we’re seeing things as they were when the photons left, not as those objects are today. (And I’ve looked at objects over a billion light-years away!) It’s very humbling, really. And yet, the ability to look up and accurately perceive these wonders seems miraculous. That’s what makes astronomy a truly spiritual endeavor.

To keep this article within bounds, we’re now going to head straight off for M4. Antares and M4 are very close together in our sky, so we can head out on almost the same heading.

M4 is about 7200 light-years from Earth. We’ve already gone 550, so that leaves 6650 to go. It also means that M4 is twelve times farther away than Antares. Yet, a modest telescope can still easily resolve individual stars in the cluster.

Antares is part of the galactic disc, orbiting the galactic center in much the same plane as we do. M4, however, has an orbit of its own. (We haven’t been studying it long enough to know exactly what that orbit is. Perhaps we’ll encounter an ancient civilization in the cluster that can tell us all about it!) When we get to M4, we’ll be able to look down and out across the vast expanse of the mighty Milky Way Galaxy; what a sight that must be!

This is only one of a number of flight plans I’ve put together to help me better see the Universe in three dimensions. Light may have a speed limit, but my imagination doesn’t. It’s an awfully big Universe out there (awe being the operative word). I encourage you to spend whatever time you can spare getting to know it as intimately as you can, for the Galaxy is our home every bit as much as is Tehachapi. Sending my mind deep into the Universe alw ays helps me put my earthly concerns in perspective. Yes, we’re but one small planet in a vast galaxy. Yet, each of us is endowed with the extraordinary gift of being able to perceive the heavens as they truly are. No matter how many times I try to explain what I’m seeing to my cat, all he ever cares about is whether there’s enough moonlight to catch critters. But, you get it! That’s very special. That’s why I bother to write this column.

Saturn still rules the night sky in September, its rings still stunningly tilted toward us. With quadrature on August 21st, Saturn casts an off-center shadow across its rings, making for a more three-dimensional appearance.

Sept. 23: Autumnal Equinox. Fall begins at 1:21 am.

Sept. 27: Total Lunar Eclipse. This will be the fattest eclipsed moon we will ever see, because the moon will be at the closest point in its orbit (perigee). The sun will set at 6:44 pm, with the moon rising already in partial eclipse at 6:40. Totality begins at 7:11 and ends at 8:23. Get your cameras and telephoto lenses ready; it won’t get much better than this, folks!

You may recall Venus, Mars, and Jupiter gathered together with the setting sun last month. Now they’ll be rising on the other side ahead of the rising sun.

Sunrise/Sunset: 6:26 am/7:21 pm (September 1st)