Discover the JNow RA and Dec of L4 and L5 in the Sun/Earth System

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In summary, the discussion is about the JNow Ra and Dec of the L4 and L5 points in the Sun/Earth System. The Earth/Sun L4 and L5 points are equilateral triangles on the Earth's orbit, with L4 being 60 degrees East of the Sun and L5 being 60 degrees West. Trigonometry is needed to calculate the exact positions, but this assumes a circular orbit which is not the case. It is difficult to calculate the RA and Dec of these imaginary orbits.
  • #1
Valareos
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Does anyone know the JNow Ra and Dec of the L4 and L5 points in the Sun/Earth System?
 
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  • #2
Hi,
interesting question, can't find any references on the web, so here's a couple of thoughts...

My understanding of the Earth/Sun L4 & L5 points is that they lie on the Earths orbit with the lines linking them to the Sun making 60° angles with the Earth-Sun line. So Earth/Sun/L4 and Earth/Sun/L5 are equilateral triangles (when viewed from above the plane of the ecliptic). So, L4 must be 60 degrees East of the Sun and L5 60 degrees West, along the plane of the ecliptic. So if you know the RA and Dec of the Sun, you've got a good start! (Have a look at JPL Horizons website,that should give the Sun RA and Dec for given time). Then the question becomes one of trigonometry...how to calculate the position of a point 60 degrees East(or West) of the Sun along the plane of the Ecliptic which is inclined at 23.45 degrees to the celestial sphere equator.
My trigs not that good, unfortunately! Anyone?...

NB This assumes the Earth's orbit to be circular, which it isn't, so this is only an aproximation, I guess...

Good luck,
BrianJ.
 
  • #3
Lagrangian points are actually ellipses around the Sun. They are always over an imaginare line from the Sun to our planet. ¿Can have RA and DEC, those imaginary orbits? Difficult to calc...
 

1. What are RA and Dec of L4 and L5?

RA and Dec stand for Right Ascension and Declination, respectively. They are coordinates used in astronomy to locate objects in the sky. L4 and L5 refer to the Lagrange points, which are stable points in the orbit of a planet where the gravitational pull of the planet and the Sun are balanced.

2. How are RA and Dec used to locate L4 and L5?

RA and Dec are used to determine the exact position of L4 and L5 relative to the Earth. By knowing the coordinates of these points, astronomers can point their telescopes to the correct location in the sky.

3. What is the significance of L4 and L5 in astronomy?

L4 and L5 are important points in the orbit of a planet because they are stable locations where objects can remain in a stable orbit. These points are also where Trojan asteroids, which share the same orbit as a planet, can be found.

4. Can L4 and L5 be observed from Earth?

Yes, L4 and L5 can be observed from Earth using telescopes. However, they may be difficult to see due to their small size and distance from Earth.

5. Are there L4 and L5 points for all planets?

No, L4 and L5 points are only found in the orbit of planets that are larger than their neighboring planets. For example, Earth has L4 and L5 points, but Mars does not because it is smaller than Earth.

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