<p>All the planets will have retrograde periods.  These occur as one planet overtakes another.  It is always an interior planet that overtakes an exterior one.</p>
<p>So Mars overtakes Jupiter, Saturn, Uranus and Neptune. Mars is overtaken by  Mercury, Venus, and Earth</p>
<p>For outer planets: Jupiter, Saturn, Uranus and Neptune, they will move retrograde as Mars passes them at opposition. They move retrograde when they are opposite the sun in the sky.</p>
<p>The planets inner to Mars: Mercury, Venus, and Earth will move retrograde as they overtake Mars. At this time they are close to a conjunction with the sun (so difficult to observe)</p>
<p>You can only see a crescent on the three inner planets.  For a planet to show a crescent, it must come between Mars and the sun, which is only possible for the inner planets.</p>

CC BY-SA 4.0
2021-09-19T08:07:31.483Z
2021-09-19T08:07:31.483Z
James K
<p>So I saw this question online</p>
<blockquote>
<p>If you lived on Mars, which planets would describe retrograde loops? Which would never be visible as crescent phases?</p>
</blockquote>
<p>And on a few QA website I searched, they gived totally different answers,
from <a href="https://www.jiskha.com/questions/85077/if-you-lived-on-mars-which-planets-would-describe-retrograde-loops-which-would-never-be" rel="nofollow noreferrer">Jiskha</a>, it said:</p>
<blockquote>
<p>Retrograde motion for outer (Jupiter and beyond); crescent phases for inner (Earth, Venus and Mercury).</p>
</blockquote>
<p>On <a href="https://quizlet.com/268673894/astronomy-ch-3-flash-cards/" rel="nofollow noreferrer">Quizlet</a>, it said:</p>
<blockquote>
<p>If you lived on Mars and observed the solar system from there, <strong>All other planets</strong> would describe retrograde loops, <strong>Mercury, Venus, and Earth</strong> would always be seen near the sun, and <strong>Jupiter and Saturn</strong> would never be visible as crescent phases.</p>
</blockquote>
<p>And lastly, on <a href="https://brainly.com/question/15123919" rel="nofollow noreferrer">Brainly</a>,</p>
<blockquote>
<p>If you lived on Mars and observed the solar system from there, would describe retrograde loops, would always be seen near the sun, and would never be visible as crescent phases. (We are limiting responses to the five planets you could see with the naked eye from Mars, which are Mercury, Venus, Earth, Jupiter, and Saturn.) Hint: From Earth, all the other planets show retrograde motion; Mercury and Venus are always near the sun; and Mars, Jupiter, and Saturn are never visible as crescents.</p>
</blockquote>
<p>So which one is correct, and why? Also, how do crescents related to the visibility to other stars?</p>

<orbit><retrograde-orbit>
Retrograde and Crescent Phases Visibility on Mars
Jack the Ranger
# Retrograde and Crescent Phases Visibility on Mars

(Asked by: username_0 on 2021-09-19)

So I saw this question online

> If you lived on Mars, which planets would describe retrograde loops? Which would never be visible as crescent phases?

And on a few QA website I searched, they gived totally different answers,
from [Jiskha](https://www.jiskha.com/questions/85077/if-you-lived-on-mars-which-planets-would-describe-retrograde-loops-which-would-never-be), it said:

> Retrograde motion for outer (Jupiter and beyond); crescent phases for inner (Earth, Venus and Mercury).

On [Quizlet](https://quizlet.com/268673894/astronomy-ch-3-flash-cards/), it said:

> If you lived on Mars and observed the solar system from there, **All other planets** would describe retrograde loops, **Mercury, Venus, and Earth** would always be seen near the sun, and **Jupiter and Saturn** would never be visible as crescent phases.

And lastly, on [Brainly](https://brainly.com/question/15123919),

> If you lived on Mars and observed the solar system from there, would describe retrograde loops, would always be seen near the sun, and would never be visible as crescent phases. (We are limiting responses to the five planets you could see with the naked eye from Mars, which are Mercury, Venus, Earth, Jupiter, and Saturn.) Hint: From Earth, all the other planets show retrograde motion; Mercury and Venus are always near the sun; and Mars, Jupiter, and Saturn are never visible as crescents.

So which one is correct, and why? Also, how do crescents related to the visibility to other stars?

**Tags:** orbit, retrograde-orbit


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## 1 answers

### Answer by username_1 on 2021-09-19. Score: 2 | Accepted answer

All the planets will have retrograde periods. These occur as one planet overtakes another. It is always an interior planet that overtakes an exterior one.

So Mars overtakes Jupiter, Saturn, Uranus and Neptune. Mars is overtaken by Mercury, Venus, and Earth

For outer planets: Jupiter, Saturn, Uranus and Neptune, they will move retrograde as Mars passes them at opposition. They move retrograde when they are opposite the sun in the sky.

The planets inner to Mars: Mercury, Venus, and Earth will move retrograde as they overtake Mars. At this time they are close to a conjunction with the sun (so difficult to observe)

You can only see a crescent on the three inner planets. For a planet to show a crescent, it must come between Mars and the sun, which is only possible for the inner planets.


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