# Tag Info

## Hot answers tagged ecliptic

11

Consider how far the pleiades are above the ecliptic, and how far the moon travels in a day. From this you can work the angle at which the moon must travel relative to the ecliptic, in order to cross the eliptic within a day. You can then compare this with the actual inclination of the moon's orbit to the ecliptic, and that will tell you if an eclipse is ...

11

There are few things here I think might be worth to state: The tilt of Earth is of no importance here. As the comment says what is of importance how much the Moon orbit is inclined to the ecliptic. Now, one can say that if both Sun-orbit and Moon-orbit have the same inclination to Earth equator (namely 23.5 deg) it means the Moon and Sun orbits have no ...

8

First, don't think that equinox is when the day and night are the same. It is the moment, when the sun's declination is zero, or when the sun is directly over the equator. Let me explain ... Earth is always rotating around the Sun, so declination of the Sun is always changing (except at the solstices when it stops for a minute and goes in the other way). As @...

8

The precession of the moon's orbital plane does not align it with the ecliptic plane. The angle between those two planes is approximately 5.14° (it varies by ~±0.15°, mostly due to perturbation by the Sun). Precession causes the orientation of the lunar plane to vary, but the angle between the two planes stays (almost) the same. It's very similar to the ...

7

As you said, the Sun takes a year to cycle the Zodiac, and it takes a year between two spring or autumn equinoxes. Both statements are true, but "year" in them means two different things. It takes a sidereal year to cycle the Zodiac, but it takes a tropic year to cycle between equinoxes. Since the tropic year is about 20 minutes shorter, the equinoctial ...

7

The position of the ecliptic does change, due to perturbation of other planets, but only very slowly. The invariant plane is the plane of angular momentum of the whole solar system. This is dominated by the orbital momentum of the planets, particularly Jupiter, and since other stars are much too far away to perturb the solar system, it is invariant with ...

7

Edit: Getting the exact value winds up being simple, but it was only later in the day that the answer occurred to me. All we need to do is ask for the altitude and azimuth of the Ecliptic’s south pole! The ecliptic itself will be highest above our horizon in exactly that direction, at an altitude that is exactly 90° above its pole. Thus the answer is given ...

7

They made star maps. They mapped the posiitons of stars on the imaginary celestial sphere - whch they thought was an actual physical hollow sphere surrounding the Earth at some distance. Because the earth rotates, and they thought that the Earth stood still, they believed that the imaginary celestial sphere rotated around the Earth. They saw that stars ...

6

The ecliptic was understood to be the path of the sun relative to the sky. Ptolemy believed the sky rotated daily around the Earth. All the planets, including the Moon and the Sun, shared in this motion. However, the planets had secondary motions, relative to the sky. And in particular relative to the stars that they thought were fixed to the sky. This ...

6

I wanted to ask this question even though I realized the correct geometry in the middle of typing it. So I will answer this myself. First of all, the sub-lunar point never exceeds 28.545 N/S. If you're standing at the sub-lunar point, the Moon will be directly overhead. The Moon never wanders outside this latitude bracket. But that does not mean the Moon's ...

6

The planets do not orbit in the same plane as the Earth, they are inclined by a few degrees. This means that as they orbit the sun, they are sometimes above the plane of the Earth's orbit and sometimes below. And it takes one orbital period to go the full cycle from above, to below and back to the start. The reason that they appear further from the ecliptic ...

5

Two further points to make are that: (1) because of the way we define sunrise and sunset as being when the entire Sun is below the horizon not just the centre of the Sun. (2) When the Sun is close to the horizon the Sun’s ray are refracted (bent) by the Earth’s atmosphere so that the Sun appears to be slightly higher in the sky that it would be if the ...

5

The easiest graph to consider is the graph of day-length. If the day-length varies from 8 to 16 hours, there can only be two equinoxes: At the time of equinox, the day length changes at the fastest rate, by a few minutes in temperate regions, compared to the solstices, which change by a few seconds every day. So, the equinox doesn't exist perfectly, the ...

5

The moon's orbit around the Earth is inclined at about 5° to the ecliptic So as the Earth progresses in its own orbit around the sun, the moon's altitude also changes During summers the part of the orbit on the other side of the Earth(night side) is below the ecliptic. While during winters it is the upper part which is on the night side Source

4

Mg I does indeed mean neutral magnesium atoms, but May and his collaborators weren't observing magnesium atoms orbiting in the inner Solar System -- they were seeing absorption by magnesium atoms in the Sun's atmosphere. In the optical and near-infrared, the zodiacal light is sunlight scattered/reflected by interplanetary dust particles. Not surprisingly, ...

4

Earth is a special case since the equatorial and ecliptic coordinate systems are defined in terms of its own rotation and orbit. Earth's north pole vector in equatorial coordinates is $$\vec N_{\oplus,eq} = (0, 0, 1)$$ To transform this to ecliptic coordinates, we rotate about the $x$ axis by the obliquity $\varepsilon$ = 23.44$^\circ$ and get \vec N_{\...

4

Both the equator and the ecliptic are great circles on the celestial sphere. The appearance of each on a map depends on the map projection. In an equirectangular projection centered on the equator, the equator (brown) is a straight line, and the ecliptic (blue) is approximately sinusoidal. If the same projection is centered on the ecliptic instead, the ...

4

By inspection of a star charting app, I'd say the circles lie in the celestial equator, ie declination equal 0 degrees. Stars above the circles are to the north and vice versa.

4

The equator (Earth's rotation plane) and ecliptic (Earth's solar orbit plane) cross at the vernal equinox ♈, the zero point of both right ascension and ecliptic longitude. Relative to the ecliptic, the Earth's north pole is tilted toward ecliptic longitude λ=90°, where the Sun appears at the June solstice. Constellations in that general direction are highest ...

4

The angle MSP is the inclination of Mars relative to the ecliptic plane. This is 1.851 degrees The angle MEP is the Ecliptic latitude of Mars from Earth. This angle can be greater than 1.851 degrees. M S-----------------E--------------P S is the sun E is the Earth, M is Mars and SP is the plane of the ecliptic in this cross-...

3

The tidal field of the Galaxy does lead to the oscillation of the plane of very wide binaries. The mechanism of this oscillation is identical to the Kozai-Lidov mechanism (the only difference is that in the case of KL oscillations the tidal field is generated by the averaged orbit of a tertiary stellar companion). However, if you run the numbers, the ...

3

I cant help you with skyfield, but i usually use JPL Horizons Web interface. No installation required, you can also print it in a text file if you want: https://ssd.jpl.nasa.gov/horizons.cgi Otherwise i found the documentation for skyfield: https://rhodesmill.org/skyfield/toc.html And if nothing of that works, i made a little astropy script for you from ...

3

Maps of the sky are being used to actually get to know the sky. Thus you take the map and hold it above your head (as opposed to a map of the Earth's surface where you look down on Earth). Thus East and West are switched between that two types of maps, so that directions match actual directions when viewing the map.

3

Even from Earth, the Sun passes through non-zodiac constellations (if you use IAU constellation boundaries) It spends more time in Ophiuchus than in Scorpio, for instance. From Mercury, the Sun path would deviate from the Ecliptic (which is indeed defined by the plane of the Earth's orbit). The Sun would still pass through Ophiuchus, and it would also pass ...

2

HIP 76880 = $\kappa$ Librae (V=4.72) has an Ecliptic latitude of -0.019 degrees. This is the winner amongst all stars in the Hipparco/Tycho catalogue with a Hipparcos magnitude <6. If you mean physical distance, rather than angular distance, then the sine of the ecliptic latitude must be multiplied by a distance estimate for the star. This cannot be ...

2

Regulus ($\alpha$ Leo) is the one to beat, with ecliptic latitude $\beta$ = +0.46$^\circ$ and apparent V magnitude +1.4. Some dimmer stars are closer to the ecliptic, e.g. $\alpha$ Lib ($\beta$=+0.33$^\circ$, V=+2.7), $\delta$ Gem ($\beta$=-0.18$^\circ$, V=+3.5), and $\delta$ Cnc ($\beta$=+0.08$^\circ$, V=+3.9). For more suggestions, poke around in ...

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