Q&A Series
You Asked

You Asked: Why Do We Know More About the Moon Than Our Own Oceans?

by |April 19, 2019

Got a burning question about climate change? “You Asked” is a series where Earth Institute experts tackle reader questions on science and sustainability. To submit a question, drop a comment below, message us on Instagram, or email us here.

Today’s question comes via our Earth Month Q&A on Instagram:

Why is that we know more about Moon’s surface than we do about our own ocean floors? What challenges does ocean exploration pose that makes it so difficult in the 21st century?

Answer provided by Pierre Dutrieux

pierre dutrieux

Pierre Dutrieux is an assistant research professor in Ocean and Climate Physics at Lamont-Doherty Earth Observatory.

The main reason for our lack of direct observations of our ocean floor is technological. The surface of the Earth, the Moon and/or Mars are directly illuminated by light and radio waves. So we can either use passive systems (e.g. our eyes or microscopes) or active systems like radars installed on satellites to look at the echo generated by these surfaces. Satellites can move very fast and cover very large distances very quickly, and so can map the Earth or other planets/celestial objects in just a few weeks or hours, depending of the size of the object.

Liquid water is a much different medium than air or space, and it is much more difficult for electromagnetic waves (light, radio) to transmit through water. That is why, for example, the deep ocean is completely dark. Another consequence of this is that we cannot use our cellphones underwater.

So to “see” through water, we have to use different methods. The most direct and common method uses acoustic (sound) waves to listen to the echo from the ocean floor. But that requires having an asset (e.g. a ship) blasting the sound waves (a very demanding task on the energy side) and listening to the echo. Ships and other marine vehicles are not fast, so they cannot cover vast distances in a short amount of time, unlike satellites.

Scientists have been working to map the ocean floor for many decades. Lamont has been a pioneer in that regard. But there is still a large swath of the ocean floor that remains unexplored.

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Alexa
Alexa
1 year ago

“However, global warming has been wringing the life from the Great Barrier Reef. The warming ocean has “bleached” the corals, leaving whole sections of the reef dead and white. A recent study reports that the Great Barrier Reef has lost more than half its coral populations since 1995.” Respond to this quote. For what reasons does the information in this passage concern you? For what reasons are you not concerned? As you see it, what could be done to help save the world’s coral reefs? Explain.

Alexa
Alexa
1 year ago

Some scientists say we know more about the surface of the Moon than we do about the ocean floor. Why do you suppose this might be true? Explain. As you see it, which is potentially more important for humans to understand: the Moon, or the Earth’s oceans? Give reasons to support your response.

Krystal
Krystal
1 year ago

I see no reason to even attempt to go to Mars, or any other planet as we have, when we can’t even map the ocean. Solve that challenge first. If the true excitement in space, is the possibility of life, considering the constant discovery of new life in our oceans and the intimate relationship they would have on any life-bearing planet, it is simply skipping far too many steps to venture even one foot off this planet until we literally know all there is to know of it.

Europa a Moon that excites so much for it’s possible possession of a liquid ocean beneath an icy crust would be a planet entirely composed of something we know little about. Titan, an exciting planet we are launching a massive endeavor soon to explore due to its methane oceans, oceans both alien to us, and we are uninterested, in being able to truly know anything about.

It is not, a fools errand to turn our gaze inward, for such insight has never failed anyone willing to venture its depths. The universe in its scarcity, has given us a message, that to know it, we must know ourselves, and this here is possibly one of the greatest of mankind’s frontiers and we don’t even know it yet… not because we don’t want to, but because we can’t…

Isn’t that unacceptable?

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Reply to  Krystal
1 year ago

who am i i died 5 years ago:) shh dont tell anyone that i’m a soul

Peter Castro
Peter Castro
1 year ago

Makes no sense! Darkest can’t be the reason, how else do we see in the dark?