Exercise helps prevent depression

I know that it’s hard to do anything when you’re depressed. Not just in the dumps, but clinically depressed. But if you can just get yourself to exercise, you might help lower the depression. A recent longitudinal study shows that exercise can help avoid depression in the first place.

Getting started is very difficult when you’re depressed–you may not see the point in trying. But if you can, then you might want to try not breaking the chain to keep at it.

How did the Moon form?

The current theory on the formation of the moon is that during the early solar system, a body around the size of Mars impacted the forming Earth and the ejecta formed the moon. Unfortunately, recent modeling shows that in this case, lunar material would mostly come from the impactor. Since the lunar material is very similar to Earth, this means the impactor would have to have had the same composition as Earth. Rather unlikely.

Other hypotheses have been put forward.

First, a smaller impactor hitting a fast spinning Earth. This makes a moon of the right size, with most material from Earth.

Second, the proto-Earth and the impactor are about the same size. This will give a full size Earth and Moon with a composition that is a mix of the 2 bodies.

The main problem with them seems to be that there is way too much angular momentum after the impact. The hypotheses have ways to shed this extra momentum, but it seems to be stretching it. They require more things to happen. It’s getting more complicated (and contrived) than the nice, simple (and likely wrong) single impact theory.

Happy Mole Day


Hope everyone has a happy mole day. October 23rd is mole day because 1 mole is 6.022 × 1023 particles. 10/23, get it?

OK. Yes, it’s silly. But a mole is a huge number that is very important in chemistry.

Teaching with Portals

Portal 2 is a game where you have to use portal guns to create teleportation fields to move around and survive. I’ve head about teachers using it for lessons, especially for physics, but I haven’t had the chance to look into it. There is a website teachwithportals.com which has lesson plans for use with Portal 2. Surprisingly with Language Arts lessons as well as science. I’ll have to look into this.

Hormone might be used to help people quit smoking

Blocking the hormone GLP-1 can make the brain not reward you for smoking nicotine. An article in NordicScience says that this hormone is used to provide the feeling of reward when smoking, and other things. Blocking this hormone should make it easier to quit smoking. They used the drug Ex-4 (Exendin-4) which simulates GLP-1, and found that it reduced the effects of nicotine.

The researchers concluded that GLP-1 receptors regulated the effect of nicotine on the reward functions in the brains of mice, and that Ex4 diminished the effect of nicotine.

This can also be used for alcohol, cocaine, and amphetamines. Hopefully this new approach can help people quit.

The full journal article is available for free.

However, there are many things that need to be tested before this can become a medicine to help people. Does it work in people as well as in mice? Doing trials. Getting regulatory approval. If it works as hoped, it will take years for this to be available.

Moving … the new fad diet!

Did you know that how much you weigh in your hometown is different from what you would weigh if you moved somewhere else? Since weight is caused by how much gravity is pulling you down onto whatever surface you’re on right now, it changes depending on where you are. If you’re on the moon, you would weight 1/6th your regular weight, because the moon’s gravity is 1/6th of Earth’s.

But it also changes for different locations on the Earth. You would weigh slightly less on the summit of Mt. Everest, because you’d be further away from most of the Earth’s mass. Or at least, further away from mean sea level, which is closer to where things are normally weighed. It’s even different depending on what city you’re in. If your scale is accurate to more than 2 decimal place, you should calibrate it with a standard mass when you move it far away.

So, if you want to weigh less, you can try going to Denver, CO, where you’ll be over 1 mile above sea level. Since you’re further away from the center of the Earth, you’ll weigh less. Not much less. And your mass will still be the same.

That’s right. Weight and mass are different things. Weight is how much gravity is pulling you down. Mass is how much matter you’re made of. So you’ll weigh less in Denver than New York (or Watchung), but your mass would be the same.

Yes, there is a conversion between them. 1 Kg is 2.2 pounds (really 2.205). And this time we are comparing apples to oranges, because grams is mass, and pounds is weight. I expect that this conversion is only valid at mean sea level at the equator.

All right, mean sea level makes sense, since that’s elevation which we just talked about. Why the equator? Because the Earth isn’t a sphere. It’s really an oblate spheroid. That means that it bulges out a little bit at the equator because of centrifugal force of its spinning. Earth’s equatorial diameter is 7926.385 miles and the polar diameter is 7899.9 miles.

I was inspired to write this post when reading http://what-if.xkcd.com/67/.

The other Pale Blue Dot

While our Earth is the original Pale Blue Dot, as imaged from Voyager 1 in 1990. Scientists have recently found another blue planet. Actually, it’s more a cobalt blue. I didn’t know about it until I read today’s XKCD comic. This planet is called HD 189773 b. This planet is a gas giant. Astronomers were able to figure out its color by looking at how the color of the host star changed when the planet went behind it. The blue colors dimmed when the planet was hidden from us. Thus, the blue planet must be blue. Cool.

Further, the probable reason it’s blue is that the atmosphere is mostly sodium, which absorbs red light. The temperature is around 1000 °C, with a variance of about 250 °C from day to night. This would make it have very strong winds, up to around 7000 kph. Temperatures this high would also cause the silicates to form glass, which would scatter blue in visible light. This planet is blue with winds over 7000 kph, and glass clouds. Now that’s cool.

Planet without a star

Recently scientists in Hawai’i have found a new planet, but this one is different. This one doesn’t have a star. Astronomers have found almost 1,000 planets outside of our solar system. But they all orbit stars. We’ve hypothesized that there are failed stars out there, that never got hot enough to start fusion in their cores, but they’re very difficult to find because they’re so dim.

But PSO J318.5-22 is about 80 light years from Earth, in the Beta Pictoris group of stars, and it isn’t orbiting a star. It’s just moving along with a group of 17 stars, in the same direction. It likely formed with them, around 12 million years ago. We found it by direct imaging, that is, by looking at it.

All the other exoplanets we’ve found have been by observing the main star and looking for wobbles caused by planets, or changes in light levels from a planet moving across the disc of the star. This makes them easier to find, but hard to study because the star outshines them.

Stars form in nebulas, large clouds of dust and gas. When the core is hot enough, with enough pressure, it stars fusing hydrogen into helium, which releases tremendous amounts of energy, forming a star. It looks like this planet, which is a gas giant, wasn’t massive enough to start fusion. There may be many other failed stars like this around, but they’re very hard to find since there isn’t a luminous star next to it.

Since PSO J318.5-22 isn’t orbiting a star, we can observe it directly. It’s a great chance to observe a failed star, soon after fusion should have started.


You may want to take a look at http://exoplanet.eu/, which has information on exoplanets.