# Tag Info

79

Human perception is generally logarithmic. For example, the perceived loudness of a sound is measured using decibels, where an decrease of $10 \text{ dB}$ divides the sound intensity by $10$. So if the eclipse were heard instead of seen, "90% coverage" might mean reducing the intensity from $120 \text{ dB}$ to $110 \text{ dB}$, a small change. Perceived ...

42

The graph looks exponential because the vertical axis is logarithmic! If you were to re-plot it as linear lumens per square meter, it would be much more v-like, or even u-like. It so happens that a logarithmic plot matches our subjective perception of light intensity better than a linear one would. That's a result of our eyes having evolved to work well in ...

40

Briefly: Because the moon's orbit "wobbles" up and down, so it isn't always in the plane of the earth's orbit around the sun. There's a 2D plane you can form from the ellipse of the earth's orbit and the sun. This plane is known as the ecliptic. The moon's orbit is not exactly in the ecliptic at all times; see this (slightly overcomplicated) picture from ...

15

The Moon's orbit is inclined with respect to the Earth's orbit. In other words, if you imagine a Sun, Earth, and Moon model sitting on a tabletop, the Sun would sit approximately still and the Earth might slide around the desktop, while the Moon would orbit the Earth, hopping up off the table, and sinking back down into it. (I used to do this demonstration ...

14

No, there is not a solar eclipse whenever we see a new moon. The reason we do not have a solar eclipse at every new moon is mostly due to the angle of Earth's axis (and by extension, the Moon's orbital plane) to the Earth-Sun line. See the diagram below (as requested) for a visual explanation. In the picture, the Sun is to the left. The upper image shows the ...

11

Since the Earth is much bigger than the Moon, (by about a factor of 4 in radius) its shadow at the distance of the lunar orbit is much larger than the Moon itself. So it is possible for the moon to spend considerable time in the Earth's shadow depending on the geometry of the eclipse. Since the Moon's orbit is inclined relative to the Earth's orbit around ...

11

The thing is, the Moon's orbital plane is slightly tilted (about 5$^\circ$) with respect to Earth's which means from the Earth's perspective that the Moon's motion oscillates around the Sun's trajectory. On most new moons, then, the Moon is either north or south of the Sun and we don't see an eclipse. For eclipses to happen, new and full moons must occur ...

10

The bigger dip comes when the cooler star passes in front of the hotter object. The reason the dip is larger in this case is the amount of light given off from the area of the hotter star which is covered by the cooler star is much larger than the amount of light given off by the same area on the cooler star. Thus when the cool star passes in front of the ...

9

A lunar eclipse occurs when the moon passes through the shadow of the Earth. That is the only configuration possible. That being said there are different type of lunar eclipses, namely total(umbral), partial, and penumbral. A total lunar eclipse occurs when the full lunar disk passes into the full shadow of the earth, the Umbra and the entire disk darkens....

8

If you think about it logically, it should be easy to visualize. In fact, the brighter star does not have to be larger necessarily. It could very well be smaller- perhaps the larger star is a red giant, while the smaller star is a blue main sequence, which has higher luminosity. In any case, the middle point of the M occurs when the star with a lower ...

8

While the chosen answer isn't incorrect it doesn't really answer the question -- that it isn't that rare on other planets. For a total eclipse you have to fall into the Umbra portion of the shadow. From this image you can see that the size of the moon and the distance from the sun as well all play an important role. If we look at the planets and moons ...

7

An excellent site for eclipse data, both lunar and solar, is NASA's Eclipse Web Site. It shows maps, tracks and illumination data for all upcoming eclipses. Find the date of the eclipse you're interested in and click on the link to find all the information you need. For example, the total lunar eclipse on June 15, 2011 has this data: Penumbral Eclipse ...

7

There's certainly no problem being out in the Sun during an eclipse: There's nothing being emitted then that's not being emitted at other times. The danger is just that the relative darkness near totality may make it seem safe to look at the Sun, even when it's not. But as long as you don't look directly at the Sun, you're fine. During the time when an ...

6

Perhaps this pdf will help. Which starts: The calculation of eclipses is chiefly a combination of geometry and orbital mechanics. Hence, it is necessary to understand the orbital mechanics involved and also the underlying geometry. The end of the pdf warns: I assume that you are not trying to do an eclipse calculation exactly. If so, the problem ...

5

The first step to observing a lunar eclipse is to make sure that it's visible from your location. This is most easily done with NASA's lunar eclipse page. Look for the calendar date that you're interested in for the eclipse, and then you can get a broad idea of what regions of the world it will be visible in. You can click the link of the calendar date to ...

5

A great site for planning eclipse viewing is one hosted by NASA. Not only does it give you information on how the eclipse will look, but it tracks information for any future eclipses. This figure gives a more detailed map. Looks like you just barely get the tail end of it. Perhaps you can plan future eclipse viewing as you peruse that NASA site and be ...

5

The moon is moving away from Earth. So in the past it was closer and its shadow was larger so a wider area experienced a total eclipse. At some point in the future (in about 0.5 Billion years) a total solar eclipse will no longer be possible because the moon's shadow won't fall on the Earth.

5

I see no reason for it, and no mention of it anywhere else. Indeed, if you look at the list of solar eclipses in the 21$^\mathrm{st}$ century, you'll see also a column containing the coordinates on the Earth's surface where the eclipse peak will be. I took that column and put it in a text editor. I then counted the number of occurrences for $^\circ N$ ...

3

If the Moon's orbit around the Earth were in exactly the same plane as the Earth's orbit around the Sun, we'd have a total solar eclipse every month (but 100% totality would be seen only from the tropics). But in fact they're not in the same plane. The Earth's spin axis is tilted by about 23 degrees relative to the Earth's orbit around the Sun, and the ...

3

You are absolutely correct, this would happen with satellites. In fact, it happens to a degree on Earth, especially if the sunset is redder than normal due to, say, a volcanic eruption. But first, let me just point out a few facts. A Lunar Eclipse is 1000 times (Or more) dimmer than at peak. Furthermore, there is a much larger difference than lit by the ...

3

It looks like you'll get a very partial solar eclipse that starts at 7:08PM local time. Sunset with a flat horizon is 7:43 local time, during which it will still be in eclipse, a little more than half-way through. The amount of eclipse is <25%, though (guesstimating, it looks to be around 15% during maximum from that lat/lon).

3

Whatever the shape of the shield is, at the telescope you're going to see the Fourier transform of it. With a simple disk shaped shield you'll see ringing artefacts at the edges and these will cause the light from the star to spill round the shield potentially hiding the planets. Generally speaking Gaussian profiles are good for this, because the Fourier ...

3

Lunar eclipses are much easier to calculate than solar ones, and it has been done over the ages via a variety of methods. E.g. there is evidence that the design of Stonehenge embodied some aspects of calculating eclipses. If we can assume that you have information on previous lunar eclipses at hand, you'll observe patterns. One of the most useful for this ...

3

It's close enough to the earth to be well within the range of solar eclipses. There's always going to be a solar eclipse somewhere in space because the moon will always cast a shadow behind it, well, except for when the moon is eclipsed by the earth. But the moon's shadow passes over the earth just a small percentage of the time. Given that the space ...

3

If one googles "probability of an exploding light bulb" one sees that it is not so rare, so coincidence will be the first hypothesis. To establish it as an observation correlated with the eclipse, one should gather "exploding bulbs" at the path of the eclipse, and at a path parallel outside the eclipse's path, in statistically significant numbers to show a ...

3

Based on my own anecdotal evidence, it doesn't. Several years ago there was a partial solar eclipse in my area. I don't remember precisely how much of the sun's disk was covered - it wasn't much, surely nowhere near 90% - but I do remember getting out of the house in the morning, thinking "hmm, it's quite dark today", then having the eerie realization that ...

2

In the graph given in your question, the middle of the 'M' dip represent the eclipse of the brighter star against the dimmer one. I see an animation from Wikipedia at http://en.wikipedia.org/wiki/Binary_star#Eclipsing_binaries that shows a small and large stare eclipsing each other. When the small one is in front you get big dip in magnitude and when the ...

2

It's amazing how long the solar eclipse myth persists in spite of attempts to educate the public. There are still school principals in many countries that deny children the opportunity to view totality, one of the most wonderful sights in nature. During partial eclipse phases, solar filters that reduce luminosity by a factor of 10^5 will permit safe viewing. ...

Only top voted, non community-wiki answers of a minimum length are eligible