Earth: A Tactile View of the Blue Marble

Getting a Feel for Eclipses Book Cover

Introduction

In July 2019, the United States celebrated the 50th anniversary of landing astronauts safely on the Moon. Although, at the time of this writing, we have yet to return humans to the Moon since 1972, we are on the precipice of sending astronauts back to the Moon and even to Mars! In addition to our nearest neighbor, the Moon, NASA has supported many more missions to various objects and locations in space involving robotic spacecraft and rovers (for more tactile resources on solar system exploration, go to sservi.nasa.gov/books/). The yearning to explore the unknown has pushed spacecrafts to the outer limits of our solar system. In addition, Earth orbiting observatories such as the Hubble Space Telescope, James Webb Telescope and Kepler have allowed us to glimpse deep into our universe, helping us unravel mysteries and discovering new ones. In the midst of our ever-expanding quest for reaching deeper into space, humankind has and always will turn their full gaze back on the planet we call home. And, from the vantage of space, precious and abundant water turns our sacred heavenly sphere into “The Blue Marble.”

The photographic library of Earth images from space is immense but all images, directly or indirectly, reveal the delicate balance between water, land and our atmosphere. For starters, check out some of the images available at https://www.nasa.gov/topics/earth/images/index.html or https://visibleearth.nasa.gov/collection/1484/blue-marble . Although the “Blue Marble” originally referred to an image taken by Apollo 17 astronauts on December 7, 1972, all images of Earth taken from space can be considered part of the Blue Marble collection.

This book commemorates a few images of Earth taken from space and allows the reader to explore them haptically, with the sense of touch. By using a variety of materials, masters were developed based on NASA images that allowed the authors to recreate some of the stunning views from space. The six-page set of “tactiles” (raised images formed from masters) will give you a feel for the grandeur of the “Blue Marble.” Each tactile has descriptive text and information highlighting the significance of the image. Scan the QR code in the lower right-hand corner of the front cover to access the text in multiple formats and audio files. Here, you can also find a version of the text in sign language.

Although we "see" in such a narrow band of the marvelous electromagnetic spectrum, we can also explore the Earth, our solar system and universe through a variety of other ways. Take time to explore this tactile with your sense of touch. You are now participating in a form of "haptic" exploration.

To develop a sense of scale and appreciation of our local region in space, Tactile 1 highlights the Earth and Moon system as a whole.

Tactile 2 zooms in on just the Blue Marble and Tactile 3 details a satellite launched in 2021 that surveys the Earth through two instruments on board.

Tactiles 4 and 5 explore the tenuous ice sheets on Greenland and Antarctica while Tactile 6 reveals the ominous view of a hurricane as seen from a satellite high above.

Tactile 1: The Earth and Moon

When trying to create models of objects in space, it is difficult to combine both size and distance in the same model because the range of sizes and relative distances are immense. This is true of objects in our solar system and all other celestial objects. With those difficulties in mind, Tactile 1 reveals 2 tactiles that show the relative sizes of Earth compared to our Moon and the average distance of the Earth to the Moon. Located on the upper left-hand side, you will find the Earth reduced in size to about 4.4 cm in diameter. If the Earth were that size, the Moon would be about 1.3 cm in diameter and is represented to the right of the Earth. Although to scale by size, these are not to scale by distance. If the Earth and Moon were those sizes, they would need to be separated by 1.4 meters!

The bottom tactile shows the relative distance of the Earth to the Moon. While greatly reducing the size of the Earth (on the left) follow along the raised line to the right until you come to the Moon. This line represents the distance of separation to scale. Another way to think about the separation is that 30 Earth’s could be stacked side-by-side to approximate the distance from the Earth to the Moon.

If you reduced the size of the Earth to the size of a basketball, the Moon would be the size of a tennis ball and would be a little over 23 feet apart! Of course, this is just an approximation of the average distance from the Earth to the Moon and it should be noted that the distance varies as the Moon’s orbit around the Earth is not a perfect circle.

Tactile 2: Earth from Space

Tactile 2 represents a satellite view of the entire Earth. By “entire” it should be noted that it is really a little less than half the earth. The other half, or hemisphere, would be blocked from view by the Earth itself. Depending on the location of the view, the Earth’s rotation would eventually bring other portions of our globe into view. In that way, tactile 2 is like a “snapshot” in time taken of one particular side of the Earth.

Start by tracing around the Earth. This defines the visible horizon of the Earth when viewed from space. The actual planet would come out of the plane of the tactile like half of a soccer ball. The back side of the Earth is not visible until it rotates into view. This view is from space and the center of the tactile is about 10⁰ south latitude and 75⁰ west longitude (for visual actual representation go to Earth from space ).

As you continue to explore, notice continents marked by a raised rough texture. Three major continents can be seen from this perspective. Can you find them? While thinking about a face of a clock, go to about the 10:00 o’clock position along the edge of the globe, you will find a ridge along the western (left) portion of one of the continents. This is part of the Rocky Mountain Chain that extends from Alaska all the way down into Mexico. Notice that the land mass narrows considerably just above the center left of the tactile. This represents the Central America region and is part of North America. A continent then blossoms to the right and center of the tactile and makes up the continent of South America. The mountain chain along the western (left) edge of this continent form the Andes Mountain Chain and extends down to about the 6:00 o’clock position at the edge of the globe.

If you go back to the 10:00 o’clock position at the edge of the globe you will again find the Rocky Mountains. Now move your finger to the east (right). This continent is North America. See if you can find another smaller ridge on the eastern edge (right side) of North America in the United States. That is the Appalachian Mountain Chain and extends from Canada down into Alabama and includes 12 other states.

Continuing to the east or right, you will find your finger on a smooth section of the tactile which makes up part of the north Atlantic Ocean. Continue east (right) and you will discover a small portion of a continent that is barely visible at about the 2:00 o’clock position on edge of the globe. That is the continent of Africa. Africa is the 2nd largest continent and yet is feels so small on this tactile. Based on your reading so far, why do you think that is so? What might we need to do in order to see the entire continent of Africa?

Besides the continents, the smoother regions of the globe represent oceans. In general, east of North and South America is the Atlantic Ocean and west of North and South America is the Pacific Ocean. Slightly above and left of center, see if you can also discover the Gulf of Mexico that lies between Mexico and Florida and the land mass just below Florida that represents the Caribbean Islands.

In the oceans, you will notice a subtle texture. Those represent clouds and are easily visible from space along with the continents. Of course, the position of the clouds is constantly changing and this tactile represents a snapshot in time.

Tactile 3: Landsat 9

Launched in 2021, this satellite will be used for years to come as it helps us detail the changes on Earth from the vantage of space. Landsat 9 website provides detailed mission information and updates and can be found at https://landsat.gsfc.nasa.gov/landsat-9/landsat-9-overview .

Landsat 9 is the big brother to Landsat 8 and Landsat 7 which are, at the time of this writing, still operational. Landsat 1 was launched in 1972 and, with the exception of Landsat 6, all have provided valuable data to our understanding of Earth by chronicling global change. Landsat satellites focus exclusively on the Earth with an occasional glimpse at the Moon for calibration purposes.

The tactile you are exploring is based off a rendered image of the spacecraft and reveals 4 major components. Before looking at each of the four components, explore the entirety of the tactile to get an idea of the overall layout. Next explore the 4 component labels and lines that direct you to the specific component which are explained below.

The large waffle textured rectangle off to the right represents the solar panel array.

Find the spacecraft body. The spacecraft body (or bus carrying the other instruments) keeps the satellite in the right orientation as it orbits the Earth. No small task for an object orbiting the Earth 14 times per day at an altitude of 438 miles (705 km) and taking over 700 images each day. It is also interesting to note that Landsat 9 covers the same place on the globe every 16 days.

Landsat 9 carries 2 instruments. The Operational Imager 2 (OLI-2) and the Thermal Infrared Sensor 2 (TIRS-2) are the “eyes” for Landsat 9. The OLI and TIRS were also the instruments onboard Landsat 8 launched in 2013, hence the dash 2 designation on Landsat 9. Although OLI-2 and TIRS-2 feature increased data resolution, the 2 instruments are redundant from Landsat 8 and previous missions, allowing Landsat 9 to provide continuity in witnessing changes on Earth over decades.

On each of the instruments, you will find a bead or bump locating the approximate position of the aperture or lens.

Tactile 4: Earth - Antarctica

The two largest ice sheets in the world cover Greenland and Antarctica. The delicate balance between global climate change and these icesheets has occupied a great deal of satellite observation time over the past several decades. Careful observations are allowing scientists to make predictions regarding local and global repercussions. Landsat 9 is helping scientists better understand the interplay of climate and icesheets.

The continent of Antarctica is a place of intrigue and wonder. Located at the apex of the south pole (right at the center of the tactile and marked by an “x” in most of these books), Antarctica boasts the largest icesheet in the world. From the orientation on tactile 4, the continent of Antarctica is centered on the globe. On the perimeter of the globe, you will find other continents that are barely visible from this vantage point. For example, towards the top of the tactile at about the 11:00 o’clock position, you will find the southern tip of South America. At the 2:00 o’clock position is a portion of Africa. Australia and New Zealand can be found at the 6:00 and 7:00 o’clock positions respectively. This tactile is to scale with Tactile 5: Earth - Greenland, which is part of the North American Continent.

The terrain on this tactile replicates the land beneath the ice sheet as determined primarily from radar soundings from satellites during NASA’s Operation IceBridge and BedMachine projects. Although idealized on this tactile, it reinforces the varying bed elevations found beneath the icesheet.

Located in the lower left-hand corner is a key that depicts penguin colonies that have been placed on the tactile. On this tactile, you will notice that the general location of five significant and large penguin colonies are marked along the coast. Can you find all of them? Each of these colonies – known as rookeries – are often very large, with upwards of a million nesting pairs at a single location! Across continental Antarctica Penguins typically breed on areas of exposed rock, with the notable exception of the emperor penguin which breeds on sea-ice.

Monitoring penguin colonies requires counting each penguin nest year after year to determine the overall health and population trends. Unfortunately, many penguin nesting areas are so remote and inaccessible that scientists often have a difficult time monitoring their populations. Fortunately, scientists have begun to increasingly rely on satellites such as Landsat for finding penguin colonies and estimating abundance.

Tactile 5: Earth - Greenland

On this tactile, the continents have a rough texture as they did on tactile 2. The middle of this tactile marks the approximate location of the Earth’s North Pole and is marked by an “x” in most of these books. Notice that the north pole is not over a continent but is found in the middle of the Arctic Ocean. Below and to the right of the north pole (middle of the tactile), you can find Greenland, which is considered part of the North American Continent. It has a smoother texture than the other continents. On this tactile the size of Greenland is to scale with the size of the continent of Antartica on the previous tactile. To the right of Greenland is the country of Iceland. A Braille label and line will guide you to this country.

Tactile 6: Severe Weather on Earth (Hurricane Structure)

Natural storms can be devastating and costly and hurricanes are one of the largest; spawning flooding, tornadoes, lightning and high winds in localized and regional areas. With the help of orbiting satellites (see Tactile 3: Landsat 9) NASA is keeping an eye on these events hoping to understand, predict and mitigate potentially disastrous outcomes. Tactile 6 represents a satellite view of a hurricane and details the structure and anatomy of these ferocious storms that often reach 483 km in diameter and even larger.

Begin by exploring the overall texture and shapes on this tactile and get a feel for the counterclockwise rotation. This counterclockwise rotation is depicted in the lower right-hand corner with the use of an arrow.

The ridges and valleys represent a satellite view of the cloud “tops.” In some areas, the clouds are higher and these ridges form what are called the spiral rainbands that appear to be emanating outwards from the center of the tactile.

At the center of the tactile a smooth region represents the “eye” of the storm. The eye can range in diameter from 20 to 40 miles (32 – 64 km) and it is here where the air converges and sinks causing the eye to be calm. Although calm, the eye acts as the pivot point or epicenter of the storm. In a tropical storm, rising warm and moist air starts rotating around a common center. This causes a region immediately surrounding the eye to rotate faster and creates the “eye wall” which can be found as the raised region directly around the eye on tactile 6. This is where some of the fastest recorded winds are found. The rotating winds fed by updrafts taking in moist ocean air towards the cloud tops then flow out over the storm clouds along the “spiral rainbands” and to the outer edge where the air sinks and is moved in towards the eye of the hurricane. This perpetuates the growth of many tropical storms into hurricane status (if the winds reach 75 mph or higher). Once the hurricane moves over land, it loses its source of moisture, and as it continues to move inland the storm weakens.

Another interesting dynamic of a hurricane can be discovered on tactile 6. Pay close attention to the height and distance from the eye that the spiral rainbands emanate from the center. On which side of the eye are they furthest away and more “dense?” This represents the strongest part of the storm and is most generally to the right of the direction the hurricane is moving. A typical hurricane moving north would then have the strongest part to the right or east of the storm. This is often called the “dirty side” of the storm and is where the most dangerous storm surges and tornadoes and high winds occur. That is due to the combination of the forward progress of the storm and the counterclockwise rotation adding to the wind speed. For example, if a storm is moving 10 mph and has wind speeds of 100 mph, then on the right side of the storm, the winds would be moving at 110 mph and on the left side of the eye, the winds would be blowing at 90 mph.

For more information regarding hurricanes, go to https://www.nhc.noaa.gov/.

Poem by Seamus Heaney

We are prepared: we build our houses squat,

Sink walls in rock and roof them with good slate.

This wizened earth has never troubled us

With hay, so, as you see, there are no stacks

Or stooks that can be lost. Nor are there trees

Which might prove company when it blows full

Blast: you know what I mean - leaves and branches

Can raise a tragic chorus in a gale

So that you listen to the thing you fear

Forgetting that it pummels your house too.

But there are no trees, no natural shelter.

You might think that the sea is company,

Exploding comfortably down on the cliffs

But no: when it begins, the flung spray hits

The very windows, spits like a tame cat

Turned savage. We just sit tight while wind dives

And strafes invisibly. Space is a salvo,

We are bombarded with the empty air.

Strange, it is a huge nothing that we fear.

Final Thoughts

This tactile set of Earth images reminds us of the fragile balance of Earth’s atmosphere, water, and land. NASA works tirelessly to monitor the health of our planet and hopes you have found this book helpful and informative. If you are interested in getting involved in science, technology, engineering or math, please reach out to one of the NASA centers or contact NASA’s office of STEM engagement at https://www.nasa.gov/stem.