<p>You should be able to answer this easily: just look up the angular subtense of the Galileans from Earth and compare with the angular subtense of our Moon from Mars (and heck, check out the ability of Martians to see their own moons :-) ).  You might also want to check out the orbital radii to ensure you can resolve the moons vs. their home planet.</p>

<p>The Galilean angular separation from Jupiter is <a href="https://en.wikipedia.org/wiki/Galilean_moons#Visibility" rel="nofollow">2 to 10 arc-minutes</a>. </p>

<p>Ganymede's diameter is 5300 km; under ideal orbital positioning, it's  <a href="https://en.wikipedia.org/wiki/Jupiter" rel="nofollow">3.95029 AU</a> , or 590 Gm from Earth, so it subtends about 2 arc-seconds (someone check my math! :-) ).</p>

<p>Our Moon's diameter is <a href="https://en.wikipedia.org/wiki/Moon" rel="nofollow">3400 km</a> and its distance from Mars, at closest approach, is <a href="https://en.wikipedia.org/wiki/Moon" rel="nofollow">about 60e6 km</a>,  for a subtense of about 12 arc-seconds.</p>

<p>That suggests our Moon is easily seen from Mars w/ Galileo's original telescope.</p>

CC BY-SA 3.0
2016-09-30T14:41:40.963Z
You can see our Moon from Mars with the naked eye. It has an apparent magnitude of about 2.
Ginasius
CC BY-SA 3.0
2016-09-30T14:46:50.023Z
@Ginasius  assuming aboriginal Martians have eyesight equivalent to Terran species :-) .   But good point!
Carl Witthoft
CC BY-SA 3.0
2016-09-30T16:06:36.060Z
And is separated from the Earth by a substantial fraction of a degree at maximum. Easy to see.
ProfRob
CC BY-SA 3.0
2016-09-30T13:41:41.663Z
2016-09-30T13:41:41.663Z
Carl Witthoft
<p>We have pictures of this, thanks to Curiousity!</p>

<p><a href="https://i.sstatic.net/Q3p2K.jpg" rel="noreferrer"><img src="https://i.sstatic.net/Q3p2K.jpg" alt="The Earth and Moon from the Martian surface"></a>
(<a href="http://www.universetoday.com/109095/you-are-here-curiositys-1st-photo-of-home-planet-earth-from-mars/" rel="noreferrer">Source</a>)</p>

<blockquote>
  <p>“A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright “evening stars,” said NASA in a statement issued today.</p>
</blockquote>

<p>So yes, you can see our moon from Mars.</p>

<p>The <a href="https://en.wikipedia.org/wiki/Extraterrestrial_skies#Earth_from_Mars" rel="noreferrer">apparent brightness of our moon from Mars is +0.9</a>. The <a href="https://en.wikipedia.org/wiki/Galilean_moons#Visibility" rel="noreferrer">apparent brightness of Jupiter's 4 biggest moons is between 4.6 and 5.6 under ideal conditions</a>.  However, while our moon can be seen visually separate from Earth from Mars, Jupiter's moons can't be distinguished from Jupiter itself with an unaided eye.</p>

CC BY-SA 3.0
2016-10-01T06:34:35.967Z
Why isn't the Moon in the image in the plane of Earth and Mars? Its orbit isn't at all that much inclined.
LocalFluff
CC BY-SA 3.0
2016-10-01T09:02:07.630Z
They are about same plane, but since Curiosity is not in the Martian poles the horizon in the image is not in the same plane. In Earth it's the same: all planets lie in the ecliptic (the same plane) but the ecliptic is not an horizontal line in our sky, except for some observers some days between the poles an the polar circles.
Pere
CC BY-SA 4.0
2022-07-24T01:50:14.950Z
you may be interested in adding an answer to [How will planets behave in the night sky as seen by Mars colonists?](https://astronomy.stackexchange.com/q/26166/7982)
uhoh
CC BY-SA 3.0
2016-09-30T18:20:59.837Z
2016-09-30T18:20:59.837Z
Cody
<p>This question arises from "<a href="https://astronomy.stackexchange.com/questions/13602/what-planet-is-better-than-earth-to-infer-solar-system-configuration?rq=1">What planet is better than earth to infer solar system configuration?</a>", where one of the answers pointed that it's easier to discover the Moon from Mars than discovering the Galilean satellites of Jupiter from Earth.</p>

<p>Then my question is:</p>

<ul>
<li>How easy (or difficult) would be to see the Moon from Mars?</li>
<li>Could it be seen with naked eye?</li>
<li>Is actually easier to see the Moon from Mars than to see the Galilean moons of Jupiter from Earth?</li>
</ul>

<p>I know there are favourable factors (Mars is closer to Earth than Earth to Jupiter, and Earth is smaller than Jupiter, so it's expected to obscure less its moon than Jupiter obscures its) and also unfavourable factors (the Moon is closer to the Earth than the Galilean moons to Jupiter, and Earth and Moon are backlit when seen from Mars). What is the overall result?</p>

CC BY-SA 3.0
2016-09-30T13:16:42.690Z
what a great question.
Fattie
CC BY-SA 4.0
2022-07-24T01:49:13.537Z
different but related: [How will planets behave in the night sky as seen by Mars colonists?](https://astronomy.stackexchange.com/q/26166/7982)
uhoh
<the-moon><mars><naked-eye>
How easy would be to see the Moon from Mars?
Pere
# How easy would be to see the Moon from Mars?

(Asked by: username_0 on 2016-09-30)

This question arises from "[What planet is better than earth to infer solar system configuration?](https://astronomy.stackexchange.com/questions/13602/what-planet-is-better-than-earth-to-infer-solar-system-configuration?rq=1)", where one of the answers pointed that it's easier to discover the Moon from Mars than discovering the Galilean satellites of Jupiter from Earth.

Then my question is:

* How easy (or difficult) would be to see the Moon from Mars?
* Could it be seen with naked eye?
* Is actually easier to see the Moon from Mars than to see the Galilean moons of Jupiter from Earth?

I know there are favourable factors (Mars is closer to Earth than Earth to Jupiter, and Earth is smaller than Jupiter, so it's expected to obscure less its moon than Jupiter obscures its) and also unfavourable factors (the Moon is closer to the Earth than the Galilean moons to Jupiter, and Earth and Moon are backlit when seen from Mars). What is the overall result?

**Tags:** the-moon, mars, naked-eye
> **Comments:**
> **username_1**: what a great question.  
> **username_2**: different but related: [How will planets behave in the night sky as seen by Mars colonists?](https://astronomy.stackexchange.com/q/26166/7982)  

---

## 2 answers

### Answer by username_6 on 2016-09-30. Score: 7 | Accepted answer

We have pictures of this, thanks to Curiousity!

[![The Earth and Moon from the Martian surface](https://i.sstatic.net/Q3p2K.jpg)](https://i.sstatic.net/Q3p2K.jpg)
([Source](http://www.universetoday.com/109095/you-are-here-curiositys-1st-photo-of-home-planet-earth-from-mars/))

> “A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright “evening stars,” said NASA in a statement issued today.

So yes, you can see our moon from Mars.

The [apparent brightness of our moon from Mars is +0.9](https://en.wikipedia.org/wiki/Extraterrestrial_skies#Earth_from_Mars). The [apparent brightness of Jupiter's 4 biggest moons is between 4.6 and 5.6 under ideal conditions](https://en.wikipedia.org/wiki/Galilean_moons#Visibility). However, while our moon can be seen visually separate from Earth from Mars, Jupiter's moons can't be distinguished from Jupiter itself with an unaided eye.

> **Comments:**
> **username_7**: Why isn't the Moon in the image in the plane of Earth and Mars? Its orbit isn't at all that much inclined.  
> **username_0**: They are about same plane, but since Curiosity is not in the Martian poles the horizon in the image is not in the same plane. In Earth it's the same: all planets lie in the ecliptic (the same plane) but the ecliptic is not an horizontal line in our sky, except for some observers some days between the poles an the polar circles.  
> **username_2**: you may be interested in adding an answer to [How will planets behave in the night sky as seen by Mars colonists?](https://astronomy.stackexchange.com/q/26166/7982)  

---

### Answer by username_3 on 2016-09-30. Score: 2

You should be able to answer this easily: just look up the angular subtense of the Galileans from Earth and compare with the angular subtense of our Moon from Mars (and heck, check out the ability of Martians to see their own moons :-) ). You might also want to check out the orbital radii to ensure you can resolve the moons vs. their home planet.

The Galilean angular separation from Jupiter is [2 to 10 arc-minutes](https://en.wikipedia.org/wiki/Galilean_moons#Visibility).

Ganymede's diameter is 5300 km; under ideal orbital positioning, it's [3.95029 AU](https://en.wikipedia.org/wiki/Jupiter) , or 590 Gm from Earth, so it subtends about 2 arc-seconds (someone check my math! :-) ).

Our Moon's diameter is [3400 km](https://en.wikipedia.org/wiki/Moon) and its distance from Mars, at closest approach, is [about 60e6 km](https://en.wikipedia.org/wiki/Moon), for a subtense of about 12 arc-seconds.

That suggests our Moon is easily seen from Mars w/ Galileo's original telescope.

> **Comments:**
> **username_4**: You can see our Moon from Mars with the naked eye. It has an apparent magnitude of about 2.  
> **username_3**: @Ginasius  assuming aboriginal Martians have eyesight equivalent to Terran species :-) .   But good point!  
> **username_5**: And is separated from the Earth by a substantial fraction of a degree at maximum. Easy to see.  

---

