The ‘Blue Marble.’ NASA scientific camera aboard the Deep Space Climate Observatory (DSCOVR) satellite returned this view of Earth on July 6, 2015, from a distance of one million miles. The DSCOVR satellite is a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA. Credit: NASA
In December 1968, the crew of Apollo 8 became the first humans to leave Earth orbit and head for the moon. They also became the first to look back at their home planet and see the entire world in one glimpse. The view they shared had an everlasting impact.
Photographs of the Earth taken on the Apollo lunar voyages provided a view known as the “blue marble.” One of the best-known NASA pictures is the image of the Earth rising above the desolate surface of the moon.
“It’s the picture that was credited with starting the environmental movement,” wrote author Jeffrey Kluger, referencing the Earthrise photo in a 2013 article for Time magazine.
In Life Magazine’s “100 Photographs that Changed the World” edition published in 2003, renowned wilderness photographer Galen Rowell called the Earthrise photo, “the most influential environmental photograph ever taken.”
Message from the NASA Administrator
At NASA, it’s Earth Day every day as 20 missions continuously orbit the planet to study climate change, the behavior of oceans, precipitation worldwide, and many other Earth vital signs that help us become better stewards of our home. The International Space Station has also become an important platform for studying and learning about our planet and giving people real-time images of what is going on — from wildfires to hurricanes to the serenity of its deepest forests.
As we celebrate Earth Day this year, it’s with a new set of Earth Expeditions around the world from the edge of the Greenland ice sheet to the coral reefs of the South Pacific that will delve into challenging questions about how our planet is changing and what impacts humans are having on it.
While Earth science field experiments are nothing new for NASA, the next six months will be a particularly active period with eight major new campaigns taking researchers around the world on a wide range of science investigations. The public is invited to follow this journey of exploration online through NASA’s social media channels and the new Earth Expeditions webpage at: http://www.nasa.gov/earthexpeditions The page will feature regular video, photos and blog posts from these missions and other ongoing field activities.
One of our top Earth scientists, Dr. Michael Freilich, has said, “Combining the long-term global view from space with detailed measurements from field experiments is a powerful way of deciphering what’s happening in our world, and scientists worldwide use NASA Earth science field data together with satellite data and computer models to tackle many of today’s environmental challenges and advance our knowledge of how the Earth works as a complex, integrated system.” I couldn’t agree more. That’s one reason Earth science is such a big priority at NASA, and why it is critical to the next generation.
Of course, your most personal connection to the planet is where you live, so we’ve also launched a social media campaign with the hashtag #24Seven for people worldwide to upload photos of what they’re doing to celebrate Earth Day and improve our home planet. In return, NASA also will share what makes up a “day in the life” of NASA Earth science, capturing everything that’s involved in better understanding and protecting our home planet. You can see those images at:
NASA uses the vantage point of space to increase our understanding of our home planet, improve lives and safeguard our future. We develop new ways to observe and study Earth’s interconnected natural systems with long-term data records, share this unique knowledge, and work with institutions around the world to gain new insights into how our planet is changing. It’s a big job, but people everywhere are joining us. There’s no more important planet than Earth, and I invite you to celebrate it with us this Earth Day.
Significant Contributions Lunar Exploration has Made to Better Understand Planet Earth
Dr. David Kring, Geologist and Senior Staff Scientist at the Lunar and Planetary Institute (LPI) in Houston points out how lunar exploration has altered our view of Earth, its ecosystems, and the evolution of a habitable world. Because Earth Day’s origins can be traced to the Apollo missions, it is only fitting to recognize the significant contributions lunar exploration has made to better understand planet Earth over the last four decades.
1. It is no accident that the first Earth Day (1970) occurred a few months after the first Apollo landing (1969). Views of whole Earth hanging in space as a singular home for all humanity were first generated by the Apollo 8 crew when they made their pioneering orbit of the Moon and by subsequent lunar missions, including a favorite “Earthrise” view of Apollo 11 and the final view from Apollo 17 that NASA often uses to describe Earth as an “isolated ecosystem floating in space.” Having witnessed the beauty of those views, NASA has continued to capture images from space and created the stunning “Blue Marble” views of our planet.
2. Exploration of the Moon taught us that Earth probably formed in a catastrophic impact with another planet half its size about 4.5 billion years ago. That collision threw a cloud of debris into orbit around Earth that eventually accreted to form the Moon. From that moment, the environment of Earth began to evolve into the life-sustaining planet we now enjoy.
3. Exploration of the Moon and, in particular, analyses of lunar rocks taught us that the Earth-Moon system continued to be bombarded by asteroids and comets. There may have been a particularly intense period of bombardment ~3.9 to 4.0 billion years ago that is nearly coincident with the earliest evidence of life on Earth. That coincidence has caused geologists to wonder if this bombardment may be implicated in the origin and early evolution of life on Earth.
4. The impact bombardment that preceded that earliest evidence of life resurfaced Earth, so it looked like the heavily cratered surfaces of the Moon, Mars, and Mercury. It destroyed a lot of the rocks on the surface, so we are left with only a few mineral zircon relicts that are older than 3.9 billion years.
5. Analyses of these impact events also teach us that the bombardment, while dramatic, did not deliver Earth’s water. Rather, Earth’s water was delivered in an earlier epoch prior to 4 billion years ago. The seas of Earth appear to be a very early evolutionary feature.
6. Lunar exploration further caused geologists to wonder if impact events may have affected the later evolution of life on Earth. That revolutionary idea led to the impact-mass extinction hypothesis and the realization that an asteroid impact terminated the age of dinosaurs and ushered in the age of mammals.
7. Many calamities in Earth history were caused by an impact’s ability to severely alter global environments and cause ecosystems to collapse. The Chicxulub impact crater, for example, caused deforestation, acid rain, and greenhouse warming, which are similar to the problems that plague us today. Earth’s environment is a uniquely hospitable, but potentially fragile, place.
8. The Moon illustrates that planetary bodies too small in size and without sufficient gravity cannot hold onto an atmosphere. Earth is a clement place in part because of its large size.
9. When life formed on Earth, the Moon was much closer and appeared about 2.5 times larger in the sky. This proximity to Earth caused larger tides that may have been important to kick-start metabolic processes, and thus life, in intertidal zones. Lunar laser reflectors placed on the Moon’s surface during the Apollo missions indicate the Moon is traveling 1.5 inches per year (3.8 centimeters per year) away from Earth.
10. Without the Moon, Earth’s axis would be much less stable, causing much greater fluctuations in climate, perhaps too great for life to survive.
Because Earth lost its own geological record due to the continuous recycling of the surface, we must rely on the Moon to discover the earliest evolutionary and environmental details of our home planet. Kring says “we should celebrate this Earth Day by looking at the reflection of Earth history in the Moon.” He adds that “future lunar exploration will undoubtedly continue to enhance our understanding of the origin and evolution of life on Earth.” On this 40th anniversary celebrating our home planet, humankind must continue to look skyward to the Moon and beyond for answers to many of Earth’s unsolved mysteries.
For more information, visit http://www.lpi.usra.edu/features/EarthDay/
Posted by: Soderman/SSERVI Staff