Main Idea

Rhinoceros skin is really thick and looks like it would be extra touch and protective. Although it is pretty strong, rhino skin is actually really sensitive to insect bites and to the powerful ray of the sun. This is why rhinos spend so much time rolling around in the mud. When the mud dries on their skin, it creates a layer that helps protect them from bites and sunburns.

• A rhinoceros' horn is made of protein, not bone.

• Rhinos have sensitive skin.

• Rhinos don't see very well, but their other senses make up for it.

• Rhinos are intelligent animals.

Have you ever seen a rhinoceros' horn and wondered what it was made of? Those giant horns might look like bones, but they're actually made of the same stuff hat human hair and fingernails are made of. It's a protein called keratin. A rhino's horn actually is a bunch of hairs that grow together into one really strong mass. In fact, the hairs continue to grow as the rhino ages, so the horn does, as well. It's an amazing part of an amazing animal.

• A rhinoceros' horn is made of protein, not bone.

• Rhinos have sensitive skin.

• Rhino hairs grow long.

• Three of the five species of rhinoceros are in fear of becoming extinct.

There are 5 different species of rhinoceros. Javan, Sumatran and Indian rhinos are from Asia. Javan and Sumatran rhinos are critically endangered. This means that they are at "very high risk" of disappearing for good from the wild. The other two species of rhinos are black and white rhinos. They live in Africa. The black rhino is critically endangered. The white rhino nearly went extinct 100 years ago, but conservation efforts have helped raise the current number to 20,000.

• Rhinos have sensitive skin.

• Rhinos are intelligent animals.

• Three of the five species of rhinoceros are in fear of becoming extinct.

• A rhino horn is made of protein, not bone.

Did you know that rhinos have senses just like us? There's not exactly a great way to test a rhino's eyesight, but some who study rhinos say they can't identify objects that are only a hundred feet away. It might have something to do with rhinos having very small eyes in comparison to their body size. Luckily, the rhino has incredible hearing. It also has an amazing sense of smell. Rhinos can actually identify one another simply by smell alone.

• Three of the five species of rhinos are in fear of becoming extinct.

• Rhinos don't see very well, but their other senses help make up for it.

• Rhinos are intelligent animals.

• A rhinos' horn is made of protein, not bones.

The Grand Canyon was carved by the Colorado River over millions of years by the process of erosion. Scientists are unsure of exactly where it began. However, recent research suggests that the river started carving a number of smaller canyons as far back as 70 million years ago. The Grand Canyon as we know it today probably started taking shape around 6 to 7 million years ago.

• The Grand Canyon is a fun place to go for vacation.

• The Grand Canyon is very long and deep, but it is not the longest or deepest canyon.

• The Grand Canyon Skywalk is a popular attraction at the Grand Canyon.

• The Grand Canyon was formed by a single river years and years ago.

The Grand Canyon is incredibly long and deep, but did you know that there is another canyon that is longer and deeper? The record for the longest and deepest canyon belongs to the Yarlung Zangbo Grand Canyon in Tibet. It's over three miles down to its deepest point. That's 17,567 feet, to be exact. The Grand Canyon in Arizona is only about six thousand feet deep, about a third of the size of Tibet's canyon. They're actually pretty close in length, but the Grand Canyon is about 30 miles shorter than the 306 mile long Yarlung Zangbo.

• The Grand Canyon is very long and deep, but it's not the longest or deepest canyon.

• The Grand Canyon was formed by a single river years and years ago.

• Families love to take trips to the Grand Canyon.

• The Grand Canyon was not one of the first national parks in the United States.

As early as 1882, politicians proposed making the Grand Canyon a national park. For years, this cause had the support of powerful leaders such as President Theodore Roosevelt. Still, the Grand Canyon did not become a national park until 1919. By that point, sixteen other natural areas had already received this important status. This is pretty surprising given the widespread fame and popularity that the Grand Canyon holds today.

• The Grand Canyon is very long and deep, but it's not the longest or deepest canyon.

• The Grand Canyon was formed by a single river years and years ago.

• The Grand Canyon was not one of the first national parks in the United States.

• The Grand Canyon Skywalk is a popular attraction at the Grand Canyon.

The Grand Canyon Skywalk is one of the most popular tourist attractions at the Grand Canyon. The Skywalk is a glass walkway that hangs out over the canyon. It offers tourists incredible views to the canyon floor 4,000 feet below. Open since 2007, it becomes more popular every year. Now, more than a million visitors a year walk across the horseshoe shaped bridge to take in the wonders below. It has become a must-see attraction for many visitors to the area.

• Families love to go to the Grand Canyon for vacation.

• The Grand Canyon was formed by a single river years and years ago.

• The Grand Canyon Skywalk is a popular attraction at the Grand Canyon.

• The Grand Canyon was not the first national parks in the United States.

During the 1960's, American astronauts were celebrities. Alan Sheppard and John Glenn, two of the first Americans in space, were given parades in New York. Until then, this honor was saved for sports stars or war heroes. After returning from the moon in 1969, the Apollo 11 astronauts got a huge parade, too. In addition, spacecraft launches kept people glued to their TVs. Space missions had some of the highest TV ratings of the 1960's, showing the popularity astronauts and spaceflight at the time.

• Astronaut candidates undergo a rigorous training program.

• Astronauts were very popular with the public during the 1960's.

• Space shuttle take-offs were aired on TV.

• Astronauts made a lot of money during the 1960's.

Have you ever wondered what astronaut training is like? First, there is an entire year of intensive learning where candidates study science, the workings of space stations, and basic medical skills. Next, they go into greater detail and learn how to actually operate everything-the space station, the suits, the vehicles and more. Finally, they need to learn everything about the mission they are assigned to. They learn their roles and required skills.

• Astronauts were very popular with the public during the 1960's.

• There is an Air and Space Museum in Washington, DC.

• Astronaut candidates undergo a rigorous training program.

• Astronauts make a lot of money.