Science desk
< December 24	<< Nov \| December \| Jan >>	December 26 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

December 25

Astronomy question

Approximately what day of the year would the earth cross an imaginary line connecting the sun and the center of the Milky Way galaxy? 76.27.175.80 (talk) 00:33, 25 December 2010 (UTC)[reply]

Our Galactic Center article says that it lies in the direction of Sagittarius A*, which is on the border of the constellations Scorpius and Sagittarius. According to our Zodiac article, the Sun enters that region with respect to Earth in the early weeks of December. The Earth would therefore be on the opposite side of the Sun, ie. between the Sun and the Galactic center, half-a-year from then, or in early June. WikiDao ☯ (talk) 04:28, 25 December 2010 (UTC)[reply]

Is the Earth on the same two-dimensional access as the galaxy? Magog the Ogre (talk) —Preceding undated comment added 11:33, 27 December 2010 (UTC).[reply]

Axis, but I think you mean two-dimensional plane.

No, according to our article "The galactic plane is inclined by about 60 degrees to the ecliptic (the plane of the Earth's orbit)." My answer above is just roughly speaking. WikiDao ☯ (talk) 15:18, 27 December 2010 (UTC)[reply]

Also see here. ~A H 1^(TCU) 17:51, 27 December 2010 (UTC)[reply]

@wikidao: yes, I meant axis, but of course should have meant plane. It was an odd hour form to be up. Magog the Ogre (talk) 21:10, 27 December 2010 (UTC)[reply]

White copper peroxide

Is it true that a white and highly explosive copper peroxide can form on copper if it is exposed to air too long? --Chemicalinterest (talk) 01:46, 25 December 2010 (UTC)[reply]

Logically, that can't be true, because lots of copper is exposed to air, and it doesn't turn white or become explosive, it acquires a green patina. So, copper + air alone doesn't do it. StuRat (talk) 02:03, 25 December 2010 (UTC)[reply]

Here is a description of how to make copper peroxide: [1]. It seems to be reddish orange, not white, and there's no mention of it being explosive. StuRat (talk) 02:07, 25 December 2010 (UTC)[reply]

Hrumph. Section 10: Stability. This as well. There are some others. --Chemicalinterest (talk) 12:57, 25 December 2010 (UTC)[reply]

I don't understand. Since copper metal stands outside on roofs and such for long times, why don't they all explode, then ? StuRat (talk) 04:10, 26 December 2010 (UTC)[reply]

Maybe the rain dissolves the peroxide to make oxygen and copper oxide. But how did they get this into all their MSDS's? --Chemicalinterest (talk) 21:42, 26 December 2010 (UTC)[reply]

Species names by C. Linnaeus

How many names are unchanged since C. Linnaeus: Homo sapiens, Lemur catta, Hippopotamus amphibius, what else? Can we include that somehow in 10th edition of Systema Naturae or it's subarticles? --Eu-151 (talk) 13:05, 25 December 2010 (UTC)[reply]

Because of the Principle of Priority, many plants and animals retain the binomial names given by Linnaeus. If you look at the "What links here" page for his article (especially the links to the disambiguation page "Linnaeus"), you will find quite a few such plants and animals among the entries, as you can see by looking at their articles' infoboxes. Deor (talk) 14:11, 25 December 2010 (UTC)[reply]

Arun S Bagh question about opc drum

The original post attempted to include an image but failed to upload properly; I have removed the broken wikisyntax. Arun, please see the instructions for uploading an image, and retry posting your picture/question. Nimur (talk) 16:08, 26 December 2010 (UTC) [reply]

Are are you trying to post an image using the local file path instead of an image hosting service? That's not going to work. 81.131.30.210 (talk) 13:54, 25 December 2010 (UTC)[reply]

Here are many pictures of opc drums in case the drum type you ask about is already posted there. Cuddlyable3 (talk) 14:18, 25 December 2010 (UTC)[reply]

earth flip

I heard that the earth flips its axes where the north pole becomes the south pole. My questions are, 1. would this be notice able or will the earth do it slowly. 2. will this cause earthquakes to happen. 3. what would the climate of europe be like particularly around Ireland and britain. 4. Will it cause climate change. —Preceding unsigned comment added by 213.94.236.7 (talk) 19:44, 25 December 2010 (UTC)[reply]

I think you have some misconceptions about the switch you're thinking of. I suggest you start off at Geomagnetic reversal (which has a short Geomagnetic reversal#Effects on biosphere and human society) and come back with any questions. Nil Einne (talk) 19:50, 25 December 2010 (UTC)[reply]

Yes, the OP is surely thinking of the Earth's magnetic not geographic poles. Geomagnetic reversal#Effects on biosphere and human society notes a few speculations but we can't predict answers to questions 1 to 4. Cuddlyable3 (talk) 20:39, 25 December 2010 (UTC)[reply]

To clarify: the Earth doesn't move. The Earth's magnetic field moves. --Tango (talk) 21:16, 25 December 2010 (UTC)[reply]

There is also a fringe theory that the Earth's axis itself moves significantly: see Cataclysmic pole shift hypothesis. I don't know of any serious geologist who believes that the pole shifts a significant amount. There is, however, True polar wander: the Earth's axis of rotation wanders about on the surface of the Earth, at apparently no more than 1 degree every million years, or so. Insignificant on human timescales, but important on stellar time scales (it's thought, evidently, that Europa (moon)'s pole has shifted about 80 degrees). There is also Precession and Nutation, where the location of Earth's pole on the ground doesn't change, but the axis shifts relative to the stars. Buddy431 (talk) 23:01, 25 December 2010 (UTC)[reply]

No, it's a real worry that it's going to hit us in "about 1.5 billion years" Axial tilt#Long period variations Hcobb (talk) 05:07, 26 December 2010 (UTC)[reply]

Oh, well that saves me worrying about the sun becoming a red giant and consuming the earth, because that won't happen for five billion years! Dbfirs 17:09, 26 December 2010 (UTC)[reply]

Some proponents of the catastrophic magnetic pole shift claim that they can cause mass extinctions, which is unlikely since the last shift was over 700,000 years ago and no recorded extinction comparable to the K-T or the P-T occurred. ~A H 1^(TCU) 17:49, 27 December 2010 (UTC)[reply]

Ungulate reptile/(amphibian/bird/...)

I (by chance) met Stegosaurus ungulatus on the Stegosaurus page. Although it is a nomen dubium and usually united with S. stenops? (or armatus?), it shouldn't have it's specific epithet with no reason. And I read about a "blunt hoof" on Stegosaurine feet. Now my question: 1. Were any reptiles, especially any Dinosauria (improbable: amphibians, birds, synapsids,...), truly hooved? What about genera like Giraffatitan, Paralititan, Argentinosaurus and how the giants are called some had horns (Ceratopsia), but were there any hooved ones? Would hooves preserve in fossils? If they exist, can we cover hooved dinosaurs and their being hooved in a matter to Ungulate? Why are no dinosaurs (except for the one nomen dubium S. ungulatus) namend after being hooved? — Preceding unsigned comment added by Eu-151 (talk • contribs) 21:36, 25 December 2010 (UTC)[reply]

A proper hoof is basically a modified toenail; I don't think that any animal group besides the true ungulates walk on hoofs. --Jayron32 22:00, 25 December 2010 (UTC)[reply]

Magnet

I got a 250 pound lifting capacity magnet for Christmas. What can I do with it? I noticed that when I get close to my computer with it, the magnet changes the computer's screen color. Why? Also, I noticed that I can screw up AM radio with it. Why? Will this do any damage to the computer? Albacore (talk) 22:23, 25 December 2010 (UTC)[reply]

I'm assuming your computer has a CRT monitor? This gives a very detailed explanation for why magnets effect CRT screens. Also take a look at the Degaussing article which is related. Yes, it can sometimes permanently damage the screen. —Preceding unsigned comment added by 82.44.55.25 (talk) 22:57, 25 December 2010 (UTC)[reply]

One wonders why you got a magnet that can lift 250 lbs for Christmas if you didn't have any use for it...206.116.252.164 (talk) 01:31, 26 December 2010 (UTC)[reply]

A powerful magnet too close to your computer can also destroy your computer's hard drive; see Degaussing#Irreversible damage to some media types. Red Act (talk) 02:24, 26 December 2010 (UTC)[reply]

Agreed. Also, any magnetic media, like diskettes or tapes, could be damaged. StuRat (talk) 04:04, 26 December 2010 (UTC)[reply]

I'd be mighty careful with that. You may want to store it well away from all of your electronic devices. My dad used to wipe data off of media devices in the course of his work. I recall him saying he used magnets to do so. I'm sure that the magnets in question were nowhere near that strong. Falconus^{p t c} 05:35, 26 December 2010 (UTC)[reply]

Credit cards, too. --Mr.98 (talk) 03:19, 27 December 2010 (UTC)[reply]

To answer the "what can I do with it" question, here are some fun things you can do with magnets. Red Act (talk) 06:57, 26 December 2010 (UTC)[reply]

250 pound lifting force? Hang on! Doesn't that mean you would have to use more then 250 pounds of force to pry something off that thing? I smell a fish. I would be way too scared to play with such a magnet, imagine getting your hand (or worse) caught between a magnet like that and something attracted to it. Vespine (talk) 13:10, 26 December 2010 (UTC)[reply]

It would have to be in direct contact with a large, 100% iron object to apply the full force. Even a small offset, like that due to having your hand in between, would significantly reduce the force. StuRat (talk) 14:49, 26 December 2010 (UTC)[reply]

Permanent magnet (I assume the OP is not talking about electromagnets) lifting magnets usually have a mechanism for releasing the load when required. Example advert for the kind of size being discussed. See this video of how permanent magnet switching works. SpinningSpark 16:50, 26 December 2010 (UTC)[reply]

If you aren't careful, you can wind up pinching your fingers, causing blood blisters.[2]

<- A 250 pound lifting capacity magnet for Christmas, nice! I wonder if they make ones that work in countries that use the metric system. Sean.hoyland - talk 12:13, 27 December 2010 (UTC)[reply]

Iron magnets aren't the only items that can distort electronic screens. I once held a copper electronic coil within a flashlight arranged similar to an electromagnet too close to a TV screen, and it distorted the screen for over a week. ~A H 1^(TCU) 17:46, 27 December 2010 (UTC)[reply]