In the beginning was the Word

 

The Holy Bible was written by men divinely inspired and is God's revelation of Himself to man. It is a perfect treasure of divine instruction. It has God for its author, salvation for its end, and truth, without any mixture of error, for its matter. Therefore, all Scripture is totally true and trustworthy. – from the Basic Beliefs of the Southern Baptist Church, currently 16 million members strong

At the core of most major religions is the belief that the universe has not existed forever.  Instead, it was created by a higher power at some specific point in the past, usually to provide a backdrop or platform for humanity to inhabit. Interestingly, arguably the most profound scientific discovery of the 20^th century was that the Universe has, in fact, not been around forever.  About 13.7 billion years ago, by current best estimates, the whole enchilada started out as an almost infinitely hot and infinitely dense speck, so tiny that even our most powerful microscopes couldn’t have seen it.  From there, the speck started to expand and cool, a process that is still going on today.  This “big bang” account leaves the question of how (and, if you insist, why) the universe came into being completely open.  The Catholic Church, for example, sees in the big bang the undeniable handiwork of God the Creator.

The church may be right.  In the absence of any evidence one way or the other, divine intervention has just much right to a seat at the table as any other conjecture.  Thus, in concert with those of a religious persuasion, I’m quite open to the possibility that the Universe had a creator.  However, there is one particular religious belief concerning creation that I could not disagree more violently with: the specific details of the creation account as described in the Old Testament. Actually, to say I “disagree with” the biblical version of creation doesn’t do my position justice.  The Genesis version of the Universe’s creation can’t possibly be correct.  It’s just flat-out wrong. It’s untrue.  The sooner that all religions and denominations embrace the Catholic notion that Genesis should be taken figuratively, not literally, the better off all of us will be, believers and non-believers alike. 

This embrace cannot come fast enough for me. As recently as 2008, a Gallup poll found that fully 44% of US adults agreed with the statement "God created human beings pretty much in their present form at one time within the last 10,000 years or so”.   We can assume that a similar percentage would have agreed with the statement “God created the heavens and the Earth sometime in the last 10,000 years” as well, had this question also been asked.

So what does Genesis actually say?  Very briefly, Chapter 1 asserts that the heavens, the earth, and all living creatures, including the first humans, were created in the space of six days.  Assuming that the subsequent course of human history, as laid out in the Bible, proceeded uninterrupted from that week, various Biblical scholars have computed the time that has elapsed since that monumental week as about 6000 years. 

In this latest series of blogs, I’m going to confront this Biblical account of creation head on.  But I’m not going to go about it the standard way, which is to champion Darwinian evolutionary theory over the Genesis story of how humans came to be, or to lob geological arguments at the Young Earth Creation (YEC) movement, whose members assert that most of the geological evidence for an old Earth is instead the product of a relatively recent event - Noah’s flood.  These conventional ways of framing the issue might well be futile anyway.  In the words of the YECs themselves,

“We further deny that scientific hypotheses about Earth history may properly be used to overturn the teaching of Scripture on creation and the flood”.

So what kind of argument am I going to mount instead? I’m afraid you’ll have to check out the next blog to begin to find out!

The Difference a Day Makes

 

Last time, I explained how the movement of the Earth around the Sun creates the illusion that the Sun is moving through the zodiacal constellations.  There’s just one loose end to tie up.  At sunset, which is, as we’ve discovered, a good time to visual local motions, the Earth is moving down and to the right of the Sun; that is, the Earth is moving in the direction of a point below the western horizon.  That Earthly motion is what pushes the Sun constantly up and to the left.  Below, I’ve included the first figure from the last blog just to reinforce this point.  See how the Earth’s movement pushes it continuously to the right of the Sun?   And how that motion shifts the Sun continuously leftward?

This “cause and effect” is something to be savored, partly because you can think of it happening at any time of the day or night.  For example, remember from the “Beatles” blog that after sunset, the Earth’s rotation “pulls” the Sun along that line below your feet towards the Eastern horizon, on a course that will culminate in sunrise?  The Earth doesn’t stop orbiting the Sun just because it’s nighttime, of course, so throughout the night the Earth’s movement is constantly pushing the Sun back and to the left.  This has the effect of slowing the Sun’s forward progress to the eastern horizon, slightly delaying sunrise.  In other words, the Earth’s movement makes the nights just a little bit longer than if the Earth was stationary.  Similarly, the constant forcing of the Sun to the left during the day works to slow down the Sun’s forward motion then too, stretching out the length of the day.  The impact is small, adding only about two minutes of length to both day and night.   Still, it’s interesting to sit back and consider that each 24-hour day would be about four minutes shorter than we measure it to be if the Earth wasn’t moving around the Sun.

Now, let’s get back to how the Earth’s movement impacts our view of the stars.  I’ll ask you to once again imagine you’re out and looking up right at sunset, when the sun is barely above the western horizon.  If, every day, the sun is drifting slowly leftward, then every successive day that the sun sets, the stars that, the night before, were just far enough left of the Sun to be visible for a brief period just after sundown, before they rotated out of view, will now be swallowed up in the Sun’s glare, and disappear completely from the evening sky.  Meanwhile, in the morning sky, prior to sunrise, just the opposite will happen.  Since the Sun is drifting leftward, there’s a little sliver of sky visible just before dawn that was swallowed up in the Sun’s glare the night before.  Thus, in the early morning hours, just before sunrise, the Earth’s movement giveth; in the early evening, it taketh away.

On the scale of a single day, these effects are miniscule.  Over time, though, the evening losses and the morning gains add up until, over the course of a month, an entirely new zodiacal constellation becomes visible in the pre-dawn sky, while another zodiacal constellation disappears from the sky after sunset.  In any six-month period, these effects are enough to completely alter the pattern of stars that are visible overnight.

And that’s really all there is to it.  We’re done with our treatment of local motion, and I will wish you a brief adieu while I work on the next topic.  Until next time, Whabbloggers!

Your Sign... or Mine?

All right. In yesterday’s blog, I promised to talk about astrology, so let’s start with the most common form of astrological knowledge: your “sign”. Literally everybody knows what their sign is, right? Mine happens to be Cancer; yours is most likely one of the others, perhaps Leo, Virgo, or Libra; maybe Scorpio, Sagittarius, or Capricorn; possibly Aquarius, Pisces, Aries, Taurus, or Gemini. It is also common knowledge that our signs are dictated by the date of our birth, with each of the 12 signs roughly aligned with one of the 12 months of the calendar year.

Astrological signs are so deeply embedded in popular culture that horoscopes run everyday in major newspapers, and knowledge of one’s sign is often considered an important form of personal information (“Hi! “I’m a Cancer. What’s your sign”)? But what are astrological signs, really? Where do they come from? Why are they called “Sun” signs”? To answer these answers, I’m going to ask you to look at some familiar “landmarks”, and some familiar locations, from a new and different perspective.

If you happen to look up at the stars tomorrow night, one of the first things that will strike your eye is the fact that the stars seem to form recognizable patterns, called constellations. Each astrological sign is named after a particular constellation. People born this month are Aries, because their astrological sign corresponds to the constellation of the same name. So, when you look at the sky in April, are you able to see Aries? The answer is a most emphatic “No”! Right now, Aries is as invisible as astronomical objects ever get!

The diagram below tells the story. It depicts where the Earth is in its orbit at roughly this time of year (the illustration says “The Earth in May” instead of "The Earth in April" because a slight discrepancy has emerged over the centuries between the real position of the sun against the stars, as shown in this figure, and the designation of where the sun is in astrological terms.  I'm deliberately glossing over this discrepancy for purposes of this blog). If you draw a straight line between the Earth, and Sun, and the sky beyond, the arrow points directly at Aries. That’s why you can’t see it. Right now, the Sun and Aries occupy the same location in the sky. They rise and set together, so Aries is not visible at night.

Once the sun sets, however, other astrological (or more precisely, zodiacal) constellations ARE visible. Near the Western horizon are the constellations Taurus and Gemini. Cancer is small and not very prominent, but the big spring winner of the zodiacal constellation sweepstakes, Leo, is very prominent; you can identify Leo by the stars that are arranged in the shape of a mirror-image question mark. The other zodiacal constellations visible early tonight, Virgo and Libra, are further to the east, and harder to spot because they are lower in the sky. But, if you wait until later on, and give the Earth a chance to rotate further east, the more familiar summer constellations of Scorpio and Sagittarius will rotate into view.

But wait, you may be saying. I’ve just named the astrological signs for birthdays that come later on this summer and fall. If astrological signs are defined by which constellation the sun is aligned with that month, and the sun is in Aries right now, it must have to be shift position to align with these other constellations over the course of the next few months. That is, the sun must be moving constantly along an imaginary line that connects these constellations.

Well, it is certainly the case that the sun appears to move along such a line. The figure above tells the real story, though. It is really the Earth that is moving along its orbital track. Every day, we shift position to the right along that imaginary line by some 1.6 million miles. This movement forces the line extending from the Earth to the Sun and beyond to pivot leftward. As you can see, the effect is to “push” the Sun through the constellations that happen to be lined up with the Sun’s position in the sky: that’s what defines a zodiacal constellation. By next month, May, the Earth will have moved far enough to co-locate the Sun with the stars that make up the constellation Taurus, the Bull, which is why May babies have Taurus as their Sun sign.

Simple, right? In the figure below, we’ve fast-forwarded exactly half the year, to early November.  In that amount of time, the Earth has shifted an enormous distance, enough to push the Sun all the way to the position in the sky that’s occupied by Libra. Then, the Sun “enters” Scorpio, the sign of you mid-November babies (again, the astrological dates for Libras and Scorpios are somewhat earlier than the dates would be if the astrological dates were aligned with the actual present-day position of the Sun in relation to the zodiacal constellations).

That’s pretty much the story, Whabbloggers, at least for astrology. In the third blog of this series, I’ll return to the issue of how the apparent movement of the Sun through the zodiacal constellations changes the stars we see in the night sky. Would you care to steal my thunder by speculating on that in the comments section?

Doing the Local Motion

Last month, we discussed how the appearance and behavior of the Sun, the Moon, and Venus can be explained through the combined effects of various forms of “local” motion: the Earth and Moon rotating about their axes; the Moon revolving around the Earth; and Venus revolving around the Sun.  As you know, our own planet is in constant motion too.  Every year, the Earth completes a 600 million-mile journey around the circumference of an enormous circle with the Sun at the center (to get some idea of how truly colossal 600 million miles is, if you were to drive that distance, you would be on the road for almost a thousand years).  This translates into a constant speed of 19 miles per second, which is far faster than any supersonic jetliner, or even the shuttle.  

With the exception of the Earth’s axial rotation, which is responsible for our day/night cycle, the orbital motion of the Earth is woven more deeply into the fabric of our lives than any other form of local motion.  Consider: Virtually every one of our major sporting events, every one of our major holidays, every one of our major religious observances, and even Halloween, occurs at virtually the same time every year.  The adherence to that rigid schedule means that these shared cultural events occupy a particular point in space as well as in time.  They each have a reserved location on the Earth’s orbital path. 

The connection between these all-too-familiar activities and this underlying astronomical truth is not widely appreciated.  In part, this is due to the nature of the events themselves.  Let’s face it, folks: Tennis tournaments, football games, horse races, and Fourth of July celebrations do little to promote astronomical awareness; to the contrary, they tend to focus our attention firmly on a small piece of terra firma.  Even if we turn our attention to the objects in the sky, the impact of our orbital motion remains subtle.  There is very little hint of that motion in the behavior of the Sun, the Moon, or Venus, for instance.  Indeed, you would be hard-pressed to notice changes of any sort on a day-to-day basis (contrast that with the Moon’s orbital motion, which places it in a noticeably different location in the sky every night).  However, if we observe the night sky over a longer period of time, such as the three or so months that make up each of our seasons, the changes wrought by the motion of “Spaceship Earth” finally become apparent; so apparent, in fact, that they blow the observable effects of the other local motions completely out of the water. For, given enough time, the Earth’s journey around the Sun completely alters the thousands of stars that are visible across the night sky.

Tomorrow night, suppose you were to go out about an hour and a half after sunset and assumed the standard viewing position for our visualization exercises, which is facing due south.   Your mission, should you decide to accept it, will be to note and memorize a select few of the star patterns that you see when you look up.  Then, once a month for the next twelve months, you go out and observe again, constantly comparing the star patterns you see then with the patterns you saw the month before.

With myriads of stars to choose from, which patterns should you to focus on?  Good question.  On the one hand, I’d like you to bite off enough patterns to appreciate the breathtaking scope of the changes that the Earth’s rotation brings to the night sky.  On the other hand, I don’t want to overload your powers of observation and memorization with too many patterns.   To help me out of this dilemma, let’s restrict the objects of interest to just those star patterns that figure in that most unscientific of astronomically related disciplines: Astrology!

Astrology?  Why would a hard-nosed scientist like me want to have anything to do with astrology? As you know, I love to push back the barriers of ignorance, and going with astrology allows me to kill two “birds of astronomical ignorance” with one stone.   For the vast majority of us, astrology has something in common with the highlights of our calendar year: Although astrological concepts are embedded quite deeply into our culture and our consciousness, the connection between astrology and the Earth’s orbital motion is not widely understood.  By illustrating the effects of the Earth’s orbital movement with reference to astrological star patterns, I can make explicit the common underlying connections between astrology, the Earth’s motion around the Sun, and the changing view of the stars in the night sky throughout the year.

Am I being too ambitious here?  Perhaps, so lets create some suspense, and save the nitty gritty until the next blog.  In the meantime, feel free to share your present understanding of these connections in the comments section!