Science & Technology Quiz 2: The one with the catchy title.
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SS-18 ICBM
Oscillator
Yes, indeed. Nice and easy, wasn't it? Your go.
lovett
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Has somebody been reading the New Scientist? 
Anyway: Get one comb and one pencil. Lay you index finger atop the comb and run the pencil the side of your teeth. It should feel as if a raised dot in moving along ones finger. Apparently this is because odd sensation coming from ones teeth is similar to that of running your finger across a bump. The brain interprets it as the latter.
Anyway: Get one comb and one pencil. Lay you index finger atop the comb and run the pencil the side of your teeth. It should feel as if a raised dot in moving along ones finger. Apparently this is because odd sensation coming from ones teeth is similar to that of running your finger across a bump. The brain interprets it as the latter.
That was my question. But your answer is good.
Veritass
Emperor
Does this count?
Put blindfolded subject's left index finger in a glass of cold water and right index finger in a glass of warm water for about 15 seconds. Then put both index fingers in the same container of room temperature water and ask which one is warmer.
lovett
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Fair Enough. The New Scientist ran a few pages on tactile illusions ~2 weeks ago.Anyway: What is a 'Gravity Train'?
Well, nobody even ventured a guess! 
Can you tell us what it is, Lovett?
Meanwhile, here's an easy Open Floor question, to get the ball rolling:
The Vernal Equinox was March 20th at 11:44 UT. What exactly is the Vernal Equinox, anyway?
Can you tell us what it is, Lovett?
Meanwhile, here's an easy Open Floor question, to get the ball rolling:
The Vernal Equinox was March 20th at 11:44 UT. What exactly is the Vernal Equinox, anyway?
GoodGame
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Well, nobody even ventured a guess!
Can you tell us what it is, Lovett?
Meanwhile, here's an easy Open Floor question, to get the ball rolling:
The Vernal Equinox was March 20th at 11:44 UT. What exactly is the Vernal Equinox, anyway?
Marks the start of 'Spring', in the orbit of the Earth around the sun.
Equinoxes mark the extremes* of orbits, and also the mid points between the extremes.
*and I believe the extremes are technically referred to as apogees, with the mid-points termed epigees.
I was hoping for a little more celestial mechanics, and I believe you're mistaken about Equinoxes marking the extremes. The Solstices mark the Perihelion and Aphelion - the points in earth's orbit nearest to and furthest from the sun.
You're right about the Equinoxes being mid-way from the soltices, sort-of. Consider this: Why are there a different number of days between each of the equinoxes and solstices?
For that matter, why is spring now starting in the northern hemisphere, rather than fall?
You're right about the Equinoxes being mid-way from the soltices, sort-of. Consider this: Why are there a different number of days between each of the equinoxes and solstices?
For that matter, why is spring now starting in the northern hemisphere, rather than fall?
GoodGame
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The answer to the first question is that the orbits are elliptical, not circular, so there are 2 different sets of arcs in the orbits, of two different lengths.
Good question on the equator difference. I can't answer without Google.
This is one of those things that I find continually amazing - the dance of the sun across the sky.
There are several observed motions to consider, and when taken together as a whole, there is tremendous explanatory power:
1. The sun rises and sets once every day. Why?
2. The spot on the horizon the sun rises from and sets into changes throughout the year, a little bit each day. Which way does it go at each time of year? Why?
3. The height of the sun at midday (not necessarily noon, or 12:00) also changes every day. Why?
4. The 'seasons' change from Winter to Spring to Summer to Fall. Why?... why does it happen in that order, in both hemispheres?
5. The day of the year the solstices and equinoxes fall on changes slowly from year to year. Why?
6. Ancient people all over the globe noted the equinoxes and solstices. How did they know when it was going to happen without Google Calendar?
I'm just rambling on here... once someone offers a more complete explanation of what makes the Vernal Equinox worth noting in the calendar, they'll get the floor.
There are several observed motions to consider, and when taken together as a whole, there is tremendous explanatory power:
1. The sun rises and sets once every day. Why?
2. The spot on the horizon the sun rises from and sets into changes throughout the year, a little bit each day. Which way does it go at each time of year? Why?
3. The height of the sun at midday (not necessarily noon, or 12:00) also changes every day. Why?
4. The 'seasons' change from Winter to Spring to Summer to Fall. Why?... why does it happen in that order, in both hemispheres?
5. The day of the year the solstices and equinoxes fall on changes slowly from year to year. Why?
6. Ancient people all over the globe noted the equinoxes and solstices. How did they know when it was going to happen without Google Calendar?
I'm just rambling on here... once someone offers a more complete explanation of what makes the Vernal Equinox worth noting in the calendar, they'll get the floor.
GoodGame
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@1-----axis rotation of the Earth. edit: Rotation of the Earth around its axis.
@3-----sun's distance to the Earth changes as the Earth completes it's elliptical orbit around the sun. Of that orbit, the chord/radius from the Earth to the sun increases as the Earth goes nearer to the apogees of that orbit, which correspond to the solstice dates on the Earth.
@4-----the order of the seasons is set by the elliptical orbit of the Earth around the sun. Spring/Fall are a pair because they are opposite arcs of the orbits. Same for Summer/Winter. I'll guess the answer lies in that not only the orbit is elliptical, but also that the middle of the ellipse is not where the sun is, but actually the sun is off center---closer to the apogee that marks Summer. The sun is still equidistant to the arcs of the orbit, during the time we call Spring and Fall.
@5----I'll guess if there are changes in dates, it's because the equation of the ellipse is not perfectly constant, year to year.
@6---obviously even if the seasons didn't match, they'd all still experience the same set of arc measurements for a year, and the lengths of the arcs for Spring/Fall should still be equivalent.
@3-----sun's distance to the Earth changes as the Earth completes it's elliptical orbit around the sun. Of that orbit, the chord/radius from the Earth to the sun increases as the Earth goes nearer to the apogees of that orbit, which correspond to the solstice dates on the Earth.
@4-----the order of the seasons is set by the elliptical orbit of the Earth around the sun. Spring/Fall are a pair because they are opposite arcs of the orbits. Same for Summer/Winter. I'll guess the answer lies in that not only the orbit is elliptical, but also that the middle of the ellipse is not where the sun is, but actually the sun is off center---closer to the apogee that marks Summer. The sun is still equidistant to the arcs of the orbit, during the time we call Spring and Fall.
@5----I'll guess if there are changes in dates, it's because the equation of the ellipse is not perfectly constant, year to year.
@6---obviously even if the seasons didn't match, they'd all still experience the same set of arc measurements for a year, and the lengths of the arcs for Spring/Fall should still be equivalent.
Your'e so close, GoodGame - but you're still missing a key element 
Mise
isle of lucy
Is it the day that the Earth's tilt is exactly parallel to its direction of motion? That is, it's neither tilted towards, nor away from, the sun.
Bingo!
This results in an equal amount of daytime and nighttime in every latitude. That's what the word Equinox means: Equal Night.
The tilt of Earth's axis is the key. Without that tilt, the amount of solar radiation falling on any given spot on the planet would vary little throughout the year.
The Tilt of the Axis is the reason we have seasons.
It's why the sun appears to rise further and further north (in the northern hemisphere) as the days proceed from the winter solstice towards the summer solstice - when the rising sun stops it's pole-ward migration (Sun Stands Still: SolStice), the days stop getting longer, and then the sun starts it's southerly slide and the days get shorter.
When your hemisphere's pole is pointing towards the sun, the midday sun rises highest overhead, until the summer solstice.
Yes, the orbit of earth is elliptical, but that's much the lesser component of the story of the seasons. The tilt of the axis dominates.
Mise is up!
This results in an equal amount of daytime and nighttime in every latitude. That's what the word Equinox means: Equal Night.
The tilt of Earth's axis is the key. Without that tilt, the amount of solar radiation falling on any given spot on the planet would vary little throughout the year.
The Tilt of the Axis is the reason we have seasons.
It's why the sun appears to rise further and further north (in the northern hemisphere) as the days proceed from the winter solstice towards the summer solstice - when the rising sun stops it's pole-ward migration (Sun Stands Still: SolStice), the days stop getting longer, and then the sun starts it's southerly slide and the days get shorter.
When your hemisphere's pole is pointing towards the sun, the midday sun rises highest overhead, until the summer solstice.
Yes, the orbit of earth is elliptical, but that's much the lesser component of the story of the seasons. The tilt of the axis dominates.
Mise is up!
Mise
isle of lucy
I hate to do it again, but... OPEN FLOOR!
Perfection
The Great Head.
Cruddy Genes.
GoodGame
Red, White, & Blue, baby!
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Probably you're standing outside the ballpark hearing the game, but that's definitely not a home run, Perf.
To give two clues:
The disease involves an inflammation of the small intestine (though it might have an affect on the colon);
The body is doing something wrong in response to something.
To give two clues:
The disease involves an inflammation of the small intestine (though it might have an affect on the colon);
The body is doing something wrong in response to something.
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