So… the Earth is 6,001 years old now?

> “Cheers to a new year and another chance for us to get it right.” -Oprah Winfrey

We’ve just completed another trip around the Sun, both in terms of the calendar year, and also the way astronomers measure it, by returning once again to perihelion, the closest point in our orbit to the Sun.

If you look up at the sky, and you watch the Sun, the Moon, and the planets all move through it, you’ll notice something spectacular.

(Image credit: Larry Landolfi.)

To within a very small separation in the sky, the Sun, the Moon, and each of the planets (Venus and Saturn in this picture) all follow the same path!

Why is this?

It’s because the ecliptic plane — the plane of the Earth’s orbit around the Sun — is the same plane that all the other planets follow! To within about 7 degrees, all eight of the planets, including the asteroid belt and the Kuiper belt, orbit about the Sun in the same plane. (Individual objects, such as Halley’s Comet or Pluto, are out of the ecliptic plane due to ancient gravitational interactions.)

(The Sun’s Corona, the Moon, and Saturn, Mars, and Mercury; photo by Clementine.)

But this ecliptic plane doesn’t line up with Earth’s equator! Why not?

Because we rotate on our axis, which isn’t arbitrarily aligned with the ecliptic plane. Like pretty much all the planets do, in fact. Sure, Mercury and Jupiter are closely aligned with the ecliptic plane, but Uranus and Venus couldn’t be more anti-aligned.

(Image credit: Calvin Hamilton, and click for a huge version.)

There’s also the Milky Way galaxy, visible in dark skies, which carves a path through our night sky.

(Image credit: Kerry-Ann Lecky Hepburn.)

You will notice a very bright object in the image above, to the left of the Milky Way. That’s the planet Jupiter!

And you might ask whether our Milky Way Galaxy was either aligned with the ecliptic plane or with the Earth’s equator. What do we find?

Not at all. The galaxy is tilted at about 60 degrees with respect to the ecliptic plane, which should indicate that there’s no relationship between the Earth’s axis, the plane of the planets orbiting the Sun, and the Sun and all the other stars moving through the Milky Way Galaxy.

But there’s one more thing we can look at, beyond the Earth, beyond the Sun and the planets, even out beyond the galaxy, to see if there are any interesting alignments in our Universe.

(Image credit: WMAP.)

The Cosmic Microwave Background, of course. This relic radiation — left over from the big bang — is a fingerprint from the Universe when it was only 380,000 years old.

Here’s the odd thing. A few months ago, I wrote a post on geocentrism, and talked about some very simple observations you could make showing that the Earth was not at the center, but moved just like the other planets around the Sun. Yet little did I know that I would be faced with the following argument:

> The plane of the ecliptic- that is, the 23.5 degree inclination of the Sun and the planets with respect to Earth in their annual cycle of daily orbits- happens to be highly improbably aligned with the so-called “Axis of Evil” discovered to the very great shock of cosmologists studying the cosmic mocrowave background (CMB) in 2005, and dubbed by them the “Axis of Evil”.

This Axis of Evil is aligned in astonishingly precise ways with:

1. The Galactic North Pole 2. The ecliptic plane 3. The equinoxes

The complete ensemble of such orientations being unlikely to a combined degree of approximately one in one hundred billion.

So, let’s take a look at this so-called Axis of Evil. If I take the map from the microwave sky, I can break it down into different regions of progressively smaller and smaller sizes, and look at the fluctuations on those scales.

In physics and mathematics, we call this a multipole expansion, and we can look at the different “moments” independently.

When we do this, we find that the first moment — the monopole term (just the average temperature) — is nothing special.

(Image credit: COBE.)

Neither is the dipole term (bottom graph), which shows our motion through the sky. In fact, the small angular scales don’t show anything peculiar either.

But back in 2005, when scientists first looked at it in detail, something looked slightly amiss for the 3rd and 4th largest scales: the quadrupole and octopole moments.

It was initially claimed that this was significant: these two terms appeared to be aligned with the Earth’s axial tilt in a very unusual way. In such a way, in fact, that there was only a 1-in-2,000 chance that it would happen randomly.

But there was a problem with the analysis. You see, the map of the microwave sky I’ve been showing you doesn’t look like this. It really looks like this:

What’s all that crap in the middle? That’s the gas, dust, stars, etc., coming mostly from within our own galaxy. The problem is that it both absorbs and emits its own radiation, and that needs to be properly accounted for. When you change your model of that gas and dust, it drastically changes these quadrupole and octopole moments.

So what once looked like an extremely unlikely alignment:

(Image credit: Max Tegmark.)

Now turns out to be about as likely as you guessing the random number I chose between one and ten.

(It was eight.)

But I was very happy to hear this argument coming from someone who believes the Earth is 6,000 years old! Why?

Because the only way the Cosmic Microwave Background is meaningful in any way is if you accept the Big Bang picture of the Universe, where it’s many billions of years (13.7, to be precise) old!

It gives me hope for the new year, and not only makes me feel like we’re making progress, but also that the 13,700,000,001st year may be an even better one than the one before! Read the comments on this post…

URL: http://scienceblogs.com/startswithabang/2011/01/so_the_earth_is_6001_years_old.php

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