<p>The first image is from a July <a href="https://www.wdbj7.com/2020/07/18/five-planets-visible-in-the-early-morning-sky-this-weekend/" rel="noreferrer">article</a> by TV meteorologist Brent Watts.
Approximating that view in <a href="https://stellarium.org/" rel="noreferrer">Stellarium</a>:</p>
<p><img src="https://i.sstatic.net/Z5J1W.png" alt="Jul 19 AM sky, center alt 20 deg" /></p>
<p>The yellow arc is the <a href="https://en.wikipedia.org/wiki/Ecliptic" rel="noreferrer">ecliptic</a>, the plane of the Earth's orbit around the Sun.
It looks curved due to the <a href="https://en.wikipedia.org/wiki/Stereographic_projection_in_cartography" rel="noreferrer">map projection</a>.
If the view is centered on it, the ecliptic looks straight:</p>
<p><img src="https://i.sstatic.net/SWWas.png" alt="Jul 19 AM sky, centered on ecliptic" /></p>
<p>Unlike the Sun, which appears on the ecliptic at all times, the planets can appear a few degrees north or south of it because their <a href="https://en.wikipedia.org/wiki/Orbital_inclination" rel="noreferrer">orbital inclinations</a> are all slightly different.
The more another planet's orbit is inclined relative to ours, and the closer it approaches us, the more its ecliptic latitude varies.</p>

CC BY-SA 4.0
2020-08-10T19:09:36.170Z
2020-08-10T19:09:36.170Z
Mike G
<p>A plane looks like a curve when viewed on large angular scales on the sky (how could it be otherwise, think about a plane that cuts the north and south poles).</p>
<p>That plus the planets aren't in exactly the same plane.</p>

CC BY-SA 4.0
2020-08-10T08:14:27.670Z
2020-08-10T08:14:27.670Z
ProfRob
<p>For instance, consider the image below. The location of the planets seem to be so random relative to Earth. If the solar system was indeed flat, then I would expect the planets to lie on the same 'plane', and relative to us, it would look something like the second image. I mean, maybe Jupiter and Mars and Saturn could be on the same plane, but I fail to see how Venus would be.</p>
<p>What is wrong with my understanding here?</p>
<p><a href="https://i.sstatic.net/LXxwC.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/LXxwC.png" alt="enter image description here" /></a></p>
<p><a href="https://i.sstatic.net/j2QYX.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/j2QYX.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2020-08-10T04:27:06.730Z
There is a difference between perfectly and nearly. Zoom out to see the whole sky and show the orbits (press 'o' in stellarium)
planetmaker
CC BY-SA 4.0
2020-08-10T07:01:35.907Z
The flat plane looks likea curve when projected onto the sky.
Steve Linton
CC BY-SA 4.0
2020-08-10T09:12:55.580Z
The diagram at the top of https://en.wikipedia.org/wiki/Celestial_coordinate_system shows the ecliptic plane (the plane of the Earth's orbit) on the celestial sphere, but I admit that it's not a great diagram. A planetarium program like Stellarium is probably more useful.
PM 2Ring
<orbit><solar-system><earth>
If the solar system is nearly flat, then why don't all the planets appear to lie on the same axis when viewed from earth?
K Split X
# If the solar system is nearly flat, then why don't all the planets appear to lie on the same axis when viewed from earth?

(Asked by: username_0 on 2020-08-10)

For instance, consider the image below. The location of the planets seem to be so random relative to Earth. If the solar system was indeed flat, then I would expect the planets to lie on the same 'plane', and relative to us, it would look something like the second image. I mean, maybe Jupiter and Mars and Saturn could be on the same plane, but I fail to see how Venus would be.

What is wrong with my understanding here?

[![enter image description here](https://i.sstatic.net/LXxwC.png)](https://i.sstatic.net/LXxwC.png)

[![enter image description here](https://i.sstatic.net/j2QYX.png)](https://i.sstatic.net/j2QYX.png)

**Tags:** orbit, solar-system, earth

> **Comments:**
> **username_1**: There is a difference between perfectly and nearly. Zoom out to see the whole sky and show the orbits (press 'o' in stellarium)  
> **username_2**: The flat plane looks likea curve when projected onto the sky.  
> **username_3**: The diagram at the top of https://en.wikipedia.org/wiki/Celestial_coordinate_system shows the ecliptic plane (the plane of the Earth's orbit) on the celestial sphere, but I admit that it's not a great diagram. A planetarium program like Stellarium is probably more useful.  

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## 2 answers

### Answer by username_4 on 2020-08-10. Score: 13

The first image is from a July [article](https://www.wdbj7.com/2020/07/18/five-planets-visible-in-the-early-morning-sky-this-weekend/) by TV meteorologist Brent Watts.
Approximating that view in [Stellarium](https://stellarium.org/):

![Jul 19 AM sky, center alt 20 deg](https://i.sstatic.net/Z5J1W.png)

The yellow arc is the [ecliptic](https://en.wikipedia.org/wiki/Ecliptic), the plane of the Earth's orbit around the Sun.
It looks curved due to the [map projection](https://en.wikipedia.org/wiki/Stereographic_projection_in_cartography).
If the view is centered on it, the ecliptic looks straight:

![Jul 19 AM sky, centered on ecliptic](https://i.sstatic.net/SWWas.png)

Unlike the Sun, which appears on the ecliptic at all times, the planets can appear a few degrees north or south of it because their [orbital inclinations](https://en.wikipedia.org/wiki/Orbital_inclination) are all slightly different.
The more another planet's orbit is inclined relative to ours, and the closer it approaches us, the more its ecliptic latitude varies.


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### Answer by username_5 on 2020-08-10. Score: 1

A plane looks like a curve when viewed on large angular scales on the sky (how could it be otherwise, think about a plane that cuts the north and south poles).

That plus the planets aren't in exactly the same plane.


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