How do you locate the ecliptic?

Answer 1

While the Sun is always on the ecliptic, that's not very useful at night. The best way at night is to look for other objects that are on, or near, the ecliptic. The Moon is a good example: it's always within 5° of the ecliptic. All the planets are close to the ecliptic. Also the bright stars Regulus, Antares, Aldebaran, the Plieades, and Spica all lie close to the ecliptic.

Answer 2

The Sun is ALWAYS EXACTLY on the ecliptic. That is how it is defined. So just plot the position of the Sun. This is easier said than done since you cannot see the stars when the sun is up, so you need a way to measure positions in the sky without seeing the stars. The usual instrument is a transit circle. That is a telescope mounted so that to can move north and south but not east or west. Then you use it to watch the Sun cross the local meridian (the high noon point basically) and note the time. Then after sunset you watch some star do the same thing and note that time. The time difference tells you the east and west distance between the Sun and star in the sky, where 24 hours equals 360 degrees, and the angle north or south you had to point the telescope to catch the transit tells you the north and south distance. So it takes a transit telescope, a good clock, and meticulous record keeping to map the ecliptic. And the whole sky really. Transit observations; the grunt work of astronomy.

Answer 3

The Sun is always located in the ecliptic aside from that, it can be tricky. Part of it is passes near the east horizon and part passes near the west. If you see planets in the sky, it will also go almost through those, so you can just draw a line through any planets you see to find them. If there are no planets, it's a lot harder. You can also look for zodiacal constellations if you can find them -- that's the easiest way. You'll find them (and the ecliptic itself) on a chart, like the one you can get from Skymaps.com: http://www.skymaps.com/skymaps/tesmn0710.pdf .

Failing all of those options, you have to work it out in your head. A good way to start is to first find the equator. The equator passes through the horizon due east and due west. In the Northern Hemisphere, it rises into the southern sky, whereas it rises into the northern sky in the Southern Hemisphere. The equator comes to a maximum altitude of 90 degrees minus your latitude.

Okay, now that you've found the equator, think about where the Sun should be. During the equinox, it's on the equator. In summertime it's above, and in wintertime it's below. So if it's midnight in summer, you're looking at the part of the ecliptic that goes below the equator (since you're looking away from the Sun). So imagine a line that goes due east through the horizon, comes way up into the sky, and then comes back down to due west.

So it's really difficult if you don't have any markers to go by. It takes practice, but after a while you should be able to do this reasonably well. I hope that helps, and I wish you luck with your stargazing.

Answer 4

Mostly, the above answers are correct except for one small thing. The sun is not "exactly" on the ecliptic. There is a small offset (north/south) due to the Earth's nutation, of about 9 arc-seconds with a period of about 18.6 years.

The sun's angular size is about 32 arc-minutes, so the nutation amounts to about 0.5% of its size. You will need some good observations to detect it.

In practice, the ecliptic is located by calculation from the known position of the stars. Just about all telescope software can do this. You just aim the scope at 3 or 4 stars, and let the computer do the rest.

Answer 5

On a map of the sky, it is a great circle that cuts the celestial equator at an angle of 23.4393 degrees, marking the apparent path of the Sun over the year. It is normally marked and labelled, being an important great circle in celestial mechanics.

Because visible planets have their orbital plane very close to our orbiting plane (of which the ecliptic is the projection on the sky), if you are able to see three or four planets in the sky at the same time (including the Moon), you can "picture" the ecliptic as being the line (from horizon to horizon) that joins all the planets.

If you look at the sky and can identify the constellations of the zodiac (meaning: circle of animals), then you can imagine the ecliptic as being the line that crosses in the middle (roughly) of these constellations.

Answer 6

When you have spent a lot of time getting acquained with the constellations in the night sky over a year or more, and especially if you observe how the moon moves through the sky in a month, you will have the answer your question.

Answer 7

Trace the apparent path of the sun through the stars as the earth orbits the sun (or more likely - trace the opposite of the sun's location at night )