The Mysterious Zodiacal Light

I saw a shooting star last night when I was driving.... Then I though...hang on it's getting close to November 5th so it's probably just a firework.

Del

I've already begun to burn my neighborhood in celebration!

November 5th? Is that like the mid year celabration of Declaration of Independence?

D'uh.. no.

It's in rememberance (celebration?) of when Guy Fawkes and his co-conspirators tried to blow up the Houses of parliament.

(More religious fanatics.... Roman Catholics...
Plus ca change <exit monitor left with galic shrug>

Del

oh - and I thought you were referring to our election!

Here in the colonies, we remember Guy by holding idiotic election campaigns on or about the fifth.

During my career as a signalman in the U.S. Navy, I spent a lot of time on the signal bridge of various ships and small craft in the middle of the ocean, away from just about any artificial light, and I have seen the Zodiacal Light. It is a beautiful thing. And it makes good sense to me that it is diffused sunlight, reflecting off the dust and other small crud floating about in the plane of the ecliptic.

I don't think we really stop to think about how big and how empty our solar system really is. Think about it. Old Sol is about 1,390,000km in diameter and contains about 98% of the total mass of the solar system. Mercury, a bit less than 5000km in diameter, orbits somewhere between 46,000,000km and 70,000,000km. Venus is about 12,000km in diameter and orbits around 108,000,000km out. Earth is a bit less that 13,000km in diameter and about 150,000,000 out from the sun. Mars is less than 7000km in diameter and is between 207,000,000km and 249,000,000km out. Next is Jupiter, which is pretty stupendous at 143,000km but orbits the sun at a distance of between 740,000,000km and 816,000,000km, and it just goes on from there.

So, we have these just unbelievable distances between relatively small worlds, an a LOT of empty space in between. Even if we only consider the plane in which the planets orbit, say 10,000,000km deep and out to the orbit of Neptune, we are looking at a total volume of about 7x10²⁶ cubic kilometers! That is a huge amount of mostly empty space for small asteroids, meteors and dust to be floating around in. The total volume of the sun and all the planets combined is less than 1.5x10¹⁸ cubic kilometers, and the vast majority of that is the sun itself.

According to NASA, the Earth is struck by millions of meteors every day, but most are of course too small to even be seen. The point being that there is a tremendous amount of small stuff floating around out there to diffuse sunlight, even though in terms of the total volume of the solar system, it's pretty darned thin. A few atoms per cubit meter at best.

At a recent curriculum night at my son's school, we met with his science teacher.

To entertain us, he brought out a globe of about 18" (45.7 cm) in diameter and asked us to guess how thick the earth's atmosphere would be, relative to the size of the globe. Several guesses where in the 6" to 1' range (15 cm - 30 cm) Wrong!

He then told us that the atmosphere is about 120 miles thick (193 km) and said, "Lets take a distance on the surface of about 120 miles to establish a rough scale and see how deep that looks on the globe." WOW! It was sooooo thin, around an inch, (2.5 cm) if that much!!!

A great demonstration by a great teacher on how small and fragile our world is in the vastness of space.

I think you mean something like this.

apropo

Small things can have a big effect.

Consider this:Every human being on the planet could be contained in a cube of 1 mile each side,with plenty of room left over.A very small volume indeed.

Yet look at how much waste,toxic and otherwise, that we generate on a global basis.

We are truly the most poisonous and deadly virus to ever infect the planet, and we are changing the very planet itself.But only for a little while, in a geological time frame.

The tectonic plates continue their constant resurfacing of the Earth, and glaciers scrape the surface clean, and volcanoes lay down new surface material over the old.

Our land fills will be eventually subducted into the depths of the mantle,and recycled via volcanic eruptions into new land.

And someday, in the distant future, a new sentient species will marvel at the universe, and will give a different name to the same glow we see today.

All we can do is enjoy today as much as possible,and relish the sights and sounds around us,and marvel at the wisdom of the Great Creator.

Life is short.

In a hundred years, or less, it will not matter what we do or say here today.

As the Biblical wise man Soloman said:"Vain!Vain! All is vain."

We are truly the most poisonous and deadly virus to ever infect the planet....

This is demonstrably untrue, of course - although I did enjoy the movie.

We merely foul around the edges of our ecosphere - the real prize goes to those first simple critters that changed our atmosphere from CO₂ to oxygen, killing everything that existed before and allowing for the evolution of a whole 'nuther kind of life.

I just spent six sailboating months on the Great Lakes and have seen this phenomenon on a number of occasions. Having thought it was light coming from the city of Sudbury I paid it no further thought until I realized the positioning was off by a few degrees. I was rather mystified by this awesome event and up until reading about it now had no explanation for it...and still don't!

I live in a dark sky area in Northern Alberta, Canada. I start work very early in the morning. I've also been interested in astronomy since my childhood and read about the zodiacal light and have taken it for granted all my life.

The zodiacal light at my latitude (54N) appears all of time as a faint greenish-white conical glow that is clearly canted approximately 30 deg to 75 deg from vertical from summer to winter. The fact that it cuts across planets and the zodiac constellations "proves" it comes from things in the orbital plane of the sun.

Several engineers I work with were fooled into thinking this was dawn approaching until I explained what it was. The reaction is for people to stare in wonder (as myself) when they realize the interplanetary scale of what they are seeing.

False Dawn is what it is still called back home in NE Oregon. Nice to hear what the cause is but I've always just taken it for granted. Especially in the winter with fresh snow on the ground it can be quite bright. Of course a full Moon under the same conditions is plain irritating if you are trying to sleep.

Brad

"What's your take on the faint ghostly glow described in this SPACE.com article?"

I thought it was called sunrise, but my take is that it is what they said because they know more than I do about it.