So let's say for a second it is possible to currently pay a certain amount of money to catch a ride to the moon aboard a rocket. A dream for many of us perhaps.





You go about booking your space flight and find out that there will be a lunar or solar eclipse occurring while you are on the surface of the moon! Great right. However, it begs the question, what would you actually see? To investigate this further lets first take a look at what these two phenomenons are.









A lunar eclipse occurs when the moon passes through the shadow of the earth. In fact, you may have witnessed one before where a full moon initially will go dark, then lighten to an orange/red shade before going dark and finally back to its original state. You could have viewed it from your naked eye or perhaps after reading my telescope for beginners guide HERE , you brought a telescope and viewed it through that in much greater detail! Below is an image which shows the cycle of a lunar eclipse. If you are interested in learning astrophotography you can also check out an introduction article to it HERE .













So what is actually happening here and why does a lunar eclipse occur? For the earth to cast a shadow onto the moon, the orbital planes must be correctly aligned. Take a look at the image below.





Imagine the blue line extending horizontally from the earth represents its orbital plane around the sun. Now imagine the orange dotted line is the path the moon takes when orbiting the earth. What you may notice is that the two orbital planes are offset by 5 degrees. This means when the earth is between the sun and the moon, the moon must cross the blue line directly behind the earth (in relation to the sun) to be in the shadow of the earth. At its current position in the image, the moon can still receive sunlight from the sun as represented by the dotted yellow line hence why we do not get a lunar eclipse every time we have a full moon.





When the moon passes through the far side of the earth in relation to the sun and it crosses the earth/sun orbital plane at the same time we get a lunar eclipse. There are a few types of lunar eclipses which can occur. Before I discuss these I will briefly mention the penumbra and umbra shadows.





In a lunar eclipse, the penumbra shadow is the partial, outer shadow of the earth cast from the sun. The umbra is the area which is the dark, direct, shadow caused by the earth. The image below demonstrates this!









The first type of lunar eclipse is the penumbral lunar eclipse where the moon scrapes the earth's penumbra shadow. This type of eclipse can often be faint as the penumbra is a diffused shadow. You may also get a partial lunar eclipse where a portion of the moon goes directly into earth's umbra shadow or a total lunar eclipse where it goes completely into earth's umbra shadow. These two types of eclipses make the moon appear to go much darker and the eclipse is more pronounced.





When the moon passes in the earth's shadow, even in the umbra region, some light passes through the earth's atmosphere and bends towards the moon. Due to red light having the longest wavelength in the visible light spectrum, it gets refracted the least. Therefore, while all colours get scattered upon travelling through the earth's atmosphere, red light refracts the least and tends to make it through better than the other colours! This means the majority of light reaching the moon during an eclipse is actually red, therefore, creating a red glow. The fantastic thing about lunar eclipses is that unlike a solar eclipse, they don’t require special glasses to protect your eyes. They can be viewed on the ground or through a telescope if you have one! If you want to purchase a telescope but are unsure where to begin, check out this article made for beginners HERE .









A solar eclipse is actually extremely similar to a lunar eclipse except that this time, the moon is between the sun and earth! Just like in a lunar eclipse, in a solar eclipse, the moon casts two shadows onto the earth. The dark centre of the moon's shadow is called the umbra and the lighter, more diffused secondary shadow is called the penumbra.





If during a solar eclipse you are in the umbra shadow cast onto the earth, you will see what is known as a total solar eclipse. When this happens the sun is completely blocked by the moon plunging you into darkness. This will only occur when the sun, moon and earth are in a straight line.





In the case that you are where the penumbra shadow is, you will experience what is known as a partial, solar eclipse. In this case, there will be a darkening of the sky.





The final type of solar eclipse is known as an annular eclipse and that is where the moon is too far away from the earth to block the entire view of the sun. This produces a ring of sunlight around the moon as shown in the image below! Beware though it is still extremely harmful to look at directly with your eyes.













If you want to look directly at a solar eclipse make sure you purchase glasses made for it. You can actually get an inexpensive, certified pair from Amazon for not much more than a cup of coffee. If watching the next solar eclipse interests you, pick them up now so you have them ready. I always left it too late and by the time I got a pair the solar eclipse had already occurred (then you have to wait 18 months to see it again!) Click the image below to view them on amazon.









So, what would it all look like from the moon?





Well if you were standing on the moon whilst a lunar eclipse occurred it would look like a solar eclipse except that in this solar eclipse, the sun would pass behind the earth. Initially, when the sun appears to pass behind the earth, everything would go extremely dark on the moon's surface as it would be in the shadow of the earth! Then as the sun moves even further behind the earth we would see something we would never see during a solar eclipse from the moon.





We would see a red halo engulf the sides of the earth's atmosphere and then the surface of the moon would become a shade of red. This is because of the red light passing through the earth's atmosphere more easily than the other colours which get reflected/absorbed. The features on the earth itself would be illuminated and you would definitely need to be wearing solar glasses to watch it!





Check out the video below, it is created based off what we would see during a lunar eclipse from the surface of the moon.













But what about a solar eclipse while on the moon's surface? In that case, since we would be standing on the side of the moon closet to earth (to see earth), the sun would be on the other side of the moon meaning it would be “night time,” on the moon also known as a new moon.









When the solar eclipse occurs we would see the shadow of the moon quickly moving across the earth's surface! In the centre of the shadow would be the umbra which would be a very dark shadow cast on the earth's surface and surrounding that would be a diffused shadow which is the penumbra. Interesting the lunar reconnaissance orbiter (LRO), has actually captured an image of a solar eclipse from the perspective of the moon!





So that is it! That is what you would see from the moon during a solar and lunar eclipse. It would seem perhaps a solar eclipse is more spectacular from the earth's surface and a lunar eclipse would be quite an experience both on the earth and the moon. What do you think? Let me know by commenting below and don’t forget to put in your email address below to subscribe if you enjoyed the article and would like to see more in the future!







