A Question of Scale

Space and the universe are on my mind tonight. This was prompted by the confirmation that Voyager 1 has reached the termination shock.

The termination shock is the point in space where the stream of solar particles from our sun meet with the slower interstellar particle stream. Many researchers believe this to be a good definition of the "edge" of our solar system. Check out the science section this weekend of the New York Times online. Ken Chang has an excellent article on it.

Voyager by the way is an 815 kilogram space craft, launched in the Summer of 1977. Before personal computers and long before the internet. It's the one with that famous record on it with greetings from planet Earth to whoever finds it!

Little Voyager is now the most distant man made object from the Earth. It is an incredible 14 Billion km from home now. Looking through a window on Voyager the Sun is just a very bright star among many in the black sky.

There is a real problem with throwing a number like 14 Billion km out. It really doesn't mean anything. No one cam imagine how far that distance is.

LET'S DO BETTER

Voyager is almost 3 times further from the sun than Pluto now. But how far way is Pluto?? I can give you the true figure of 5,913 million km but that makes as much sense as 14 billion km.

LET'S DO BETTER

The Sun is 150 million km from Earth on average. We are a bit further away from the sun in Summer and closer to it in Winter. This distance is called an Astronomical Unit by Astronomers (AU). 1 AU is the distance from the Earth to the sun.


So how far away is Voyager??
93.3 Astronomical Units away from the Sun!

Pluto is at about 39 AU!

THAT MAKES MORE SENSE

If we could travel at light speed, we could circle the earth 8 times in one second. We would pass the Moon in 1.5 secs! The sun is 8.3 minutes away. We would pass Jupiter in about 40 minutes. Half an hour later would be Saturn. Finally 2.5 hours later we would pass Neptune.

It would take us a total of 5 hours and 30 minutes to pass Pluto.

Then nothing for another 7 hours until we arrived at tiny Voyager 1.

It takes over 12 hours for a radio signal from Voyager to reach earth. It is so weak that only the largest and most sensitive radio telescopes can pick it up.

Still, the nuclear reactor on Voyager will last another 15 years and if NASA budget cuts do not close up shop, we will still be able to pick it up as it sends it's last good bye home across an immense empty void.


The thing to note here, is that great distances can be put into perspective. Next time you read an article where some reporter has put some big number out. Do some calculations like I did above and send them an email....Tell them that
WE CAN DO BETTER!

Have a good weekend,
Later,
Dan

Should We Ban Dihydrogen Oxide??

There has been talk of banning this substance.

There are some good reasons for doing so.
It is very corrosive. (Darn stuff will dissolve almost ANYTHING!)
Accidentally inhaling it is often fatal.
It is a major component in acid rain as well.

Banning it won't be easy though. It is everywhere. As a matter of fact about 67% of the Earth's surface is covered with this chemical compound.

Yes I am talking about H20. Dihydrogen Oxide.
Commonly called water.

Also responsible for life in our corner of the cosmos. Kudos to this tongue in cheek web site about banning dihydrogen oxide.

Water is truly a strange and remarkable substance.

It is the only substance on earth that is common in all 3 states. Gas, liquid and vapor. It's atomic structure makes it adhesive and cohesive. Here is what I mean by that. Have you ever noticed how water clings to the side of glass as you tip it. If you look closely you will notice that in a glass, water dips down in the middle and up on the sides. You can also over fill a glass by a tiny fraction and it will not spill. That is COHESION.

Mercury is a toxic substance, but if you stick you finger in it and pull it out. Your finger will not be "wet". Try that with water. Yup, wet finger. That's ADHESION.

Most substances do not have these properties.

Water gets even stranger though. When most liquids are cooled they get more and more dense. Not water fresh water! It reaches maximum density at about 4°C. Then it gets less dense as it freezes and expands!!

The other incredible property of water is it's heat capacity. To raise 1 gram of water by 1°C takes 1 calorie of heat
(The calories on the back of your tv dinner box are 1000 times this calorie).

To raise the temperature of 1 gram of gasoline 1°C requires only half as much heat. Silver will go up 1° with 6/100's as much heat. The only common substance with a higher heat capacity than water is ammonia at 1.13 (Water is 1.00)

What this means in the real world is that water will soak up a lot of energy while raising its temperature only a little. This makes water the great moderator of our planets climate. It heats up and cools down much much more slowly than land.

If you have ever waited for a pot of water to boil, you know how much heat it takes to change water from a liquid to a vapor. The exact number is 540 calories per gram.

BUT here is the truly crucial point!

When that water vapor condenses in a thunderstorm or a hurricane back to liquid, that same 540 calories of heat is released back into the air! (Scientist call this the latent heat of condensation)

Yes, Rain actually heats up the atmosphere!!.

Hurricanes are tremendous heat engines because of this latent heat. Rain and snow are the primary way the earth moves heat from the equator to the poles. Winds and ocean currents are responsible for only about a third of the heat transfer.

This heat transfer is what makes weather. It keeps the poles from getting any colder and the tropics from getting any hotter. All because of this wierd substance called dihydrogen oxide.

I say we don't ban it after all.

Later,
Dan

This Blog is Officially METRIC

One of these days I am going to do my whole weathercast in metric units. I can hear the howls now....

Yup, This blog is metric. By the time any Meteorology student graduates there are a few things he can recite in his sleep...The hydrostatic equation (don't ask!) and metric units are among them.

Some observations about Fahrenheit versus Celsius:

One of the main tasks of the weather system we use to produce our on air weather graphics, is to convert Celsius to Fahrenheit!

The NWS converted several years back to the world standard METAR observation code and that was the end of Fahrenheit. Yes the public forecasts are still produced in the old style but the data flows around the world and across this country in Celsius now.

The digital remote thermometer on my wall at home is in Celsius too.

There are, I believe, only 3 countries that still use Fahrenheit.
Myanmar, Liberia and the USA.
I do not believe that Liberia has a weather service that issues forecasts. Not sure about Myanmar. So if you travel to these countries you will easily understand the forecast (if you speak the local language!). Anywhere else, and that includes Canada and Mexico and your forecast will be given in Metric units.

When doing calculations in school, I found that understanding metric was a big advantage. I could "tell" if my answer made sense. Many students who were used to the English system could not.

I have wondered if the above fact might be part of the reason that American students do so poorly in Math and Science compared to the rest of the industrialized world. In the latest report, USA students ranked 18th or 22nd! (Depending on how you look at the data.)

Metric may or may not be a factor,but it is a scary statistic!

I cannot recall how many times people have come up to me over the years and mentioned there love of weather and Meteorology. When asked why they did not pursue it as a career, I almost always get the same answer..."Couldn't handle all that math!"

If Celsius confuses you, don't feel too bad. I still have to convert our digital thermometer reading into Fahrenheit every day for my wife!

Later,
Dan