JJNN: Kaguya

Welcome again to JJNN for February 13th, 2009. Today we will be talking about yet another Japanese satellite.

Way back on October 27th of last year I talked about a Japanese satellite called kaguya. The last news report was about how kaguya failed to find water on the moon. This news report (found here) is about how kaguya was able to accurately map the surface of the moon.

Kaguya has been flying around the moon for a while now measuring altitude (I sort of want to say distance above sea level, but there is no sea on the moon) of the moon surface. This is the first time in history that a moon topographical map has been made with such great detail. The last moon map was made with about 270,000 data points, but the map that was made with kaguya has 6,770,000 data points. That tells a whole lot about the surface of the moon. You can see the map that was created by kaguya below.



The view below also shows the highest point (circled in black) and the lowest point (circled in white).



So, what can we learn from this map? Well, the distance around the moon at the equator is 1783.64 Km (1108.30 miles) and the distance around the moon from pole to pole is 1735.66 Km (1078.49 miles). These numbers are very close to each other, which means the moon is a near perfect sphere. It also turns out that the difference in height between the highest point on the moon and lowest point on the moon is a mere 19.81 Km (12.31 miles).

Now that kaguya has finished it's job of mapping the moon it really doesn't have anything left to do. It will fall out of orbit and crash on to the moon's surface later this year. I am sort of say to think that it is just going to end up as trash on the surface of the moon, but I guess it gave us a lot for the trade off of a little trash.

JJNN Monday: Science - 12

Welcome again to JJNN for Monday October 27th, 2008. Today we will be talking about water on the moon.

More than likely, almost as long as humans have looked up towards the moon they have wanted to try to visit it. Even Jules Verne wrote about the idea of going to the moon in his book From The Earth To The Moon. Of course that dream of visiting the moon went unaccomplished until July 20th 1969. That was a monumental day in scientific history. The only problem with going to the moon is the fact that the environment there is just not hospitable for human life. Humans need a lot of things to survive. Everything from just the right type of atmosphere to drinkable water.

There are some people that say if water (in the form of ice) is found on the moon than something can be done to make the atmosphere and make the moon habitable. The only problem with this is the fact that if there is any ice on the surface of the moon and it gets hit by sun it will go though a process known as ablation. That means the solid water will go straight to water vapor without going though the intermediate liquid step. That means as soon as there is ice on the surface it will not be there any more as soon as the sun hits it.

It sounds like there just won't be any ice on the surface, right? Well, technically, there is still hope. Scientists just have to find a place in which the sun never shines. I know that sounds like the old "Stick it where the sun don't shine!" and I guess it is close. It is more like "probe were the sun don't shine." I guess that is actually worse.

Luckily enough there are places where the sun's rays don't reach. The most promising of these places is known as the Shackleton crater. The Shackleton crater is one that lays on the south pole of the moon. The lip of the crater shields the inside from sunlight so that it is in almost constant shadow. If there is hope for ice on the moon that crater is the place to find it.

So, what if there were ice in the crater? How much ice would there be? Well the crater has a diameter of 19 km (about 12 mi) and a depth of about 2 km (just over 1 mile). If we assume that the crater is shaped like a tube (in other words no sloping sides) and was completely filled with ice it would be: pi*(19/2)^2 * 2 (this is the area of the circle at the top times the depth of the crater). This would be 567 cubic Km (or about 2625 cubic miles). If that were all water how much would it be? It turns out to be just under the amount of water in lake superior. That is a lot of water. My calculations are actually an overestimate because I am not taking into account the sloping crater walls and the fact that the crater would not be totally full of water, but it is still a whole later of water.

Last year Japan sent it's satellite named Kaguya in the direction of that crater. Kaguya is in orbit 100 km (about 62 miles) over the surface of the moon. It has a resolution of about 10 m (32 feet) per pixel. That is good resolution for a satellite of its type. You can see Kaguya below.



So, what do you think that Kaguya found in the crater? As it turns out, absolutely nothing. I guess that is an understatement because Kaguya found a lot of dirt. But, Kaguya did not find what it was looking for, ice. It is really too bad that water was not found, but there is always hope for ice in other areas of the moon. The Kaguya team is planing on going on to the north pole of the moon soon.

Any way, it is now time for the word of the day. Today's word is 月(つき). It is pronounced tsuki and means moon. The Japanese have a rabbit in the moon instead of a man in the moon.

That's it for today. See you next time at JJNN.

jjnn monday: Science - 07

Welcome again to JJNN for Monday September 15th, 2008. Today we will be talking about the moon.

During this time of year in Japan everyone is looking up into the sky. They are looking to see the wonderful full moon that is up there at the moment. This time of year is called juugo no hi and it is the traditional start of fall in the old Japanese lunar calendar.

I love the moon. I used to go out at night and just lay down in my yard and look up at it and the rest of the sky for hours. Of course August was the best time to look at the moon because you could also see the perseids meteor shower at the same time.

Since we are on the subject of the moon here are a few random facts about the moon. The moon is about 380000 km from the earth. This is one light second so when we look up at the moon we are actually seeing as it was a second ago. Some evil alien race could be destroying the moon now and we would not even know it for another second. The name of the moon came from germanic word meaning month. We only actually see one side of the moon. This is because the moon's rotation was slowed and finally locked a long time ago. The far side of the moon is a lot more boring than the side that faces us because it is almost all white. If that side of the moon ended up facing us, we would not have grown up with any man in the moon (or in the case of the Japanese a rabbit that lives on the moon and makes mochi).

Any way, this leads to this article about the moon. Tokyo's science center known as the mirai-kan decided to hang up a copy of the moon so that everyone could see it even in the middle of the day. That's a great idea I thought. The made their 6.5 meter diameter moon out of 3000 panels of diodes. You can see a picture of it below.



They dimmed the diodes or made them brighter so they fit the NASA images of the moon. I would like to see this up close but today was the last day that it was on display. Maybe next year if they bring it out again.

I will leave you with this moon related clip.



Any way, it is now time for the word of the day. Today's word is 月(つき). It is pronounced tsuki and means to moon. You know I never could see a man in the moon. My pareidolia switch must be broken.

That's it for today. See you next time at JJNN.