When we think of archaeologists, we tend to picture them sifting meticulously through dirt in search of pottery or fossils. But that image is outdated. Many of the tools that modern archaeologists use are high-tech solutions that provide lots of information without actually digging.

Some of this technology is familiar. The most common tools include portable computers and cell phones. But archaeologists use a wide range of scientific instruments, too. There are tools that help identify places of interest or locate artifacts buried underground. There is also equipment that helps analyze discoveries, revealing the age and makeup of ancient relics.

Some of the most useful technologies are those that let archaeologists study from a distance. These technologies are grouped together under the heading "remote sensing." The name describes what the technology does: It senses information without physical contact. The ability to study an area without ever setting foot on it is quite valuable. It saves time and helps control costs.

There are many different methods of remote sensing. For example, archaeologists often review pictures taken by satellites, hunting for evidence of ancient civilizations. If they find something worth a closer look, an airplane or helicopter can fly over the site to take more detailed photos.

Pictures from above May Detect Irregularities

Pictures taken from the air are particularly useful. An airplane can easily cover a great distance while providing a different view from what's visible at ground level. Sometimes, by looking down from the sky, archaeologists spot unusual formations that suggest humans have changed the land's natural geography. It might be a small mound that appears in the middle of a plain or a cliff with ridges that are too perfectly regular. These suggest new places that are worth exploring.

Sites that are too difficult to reach by foot can also be studied from above. If it's not practical to use an airplane, there are balloons or unmanned flying aircraft that can survey the area. These instruments can be operated by remote control to shoot video or take photos.

It's important that these images include many different angles. Otherwise, they can be misleading. Imagine taking a photo straight down from the sky. This angle makes everything appear flat so it's nearly impossible to distinguish hills and valleys. The same photo taken on an angle provides a completely different perspective, revealing changes in height.

Photographs work well for recording what is visible. There are other technologies, however, that help with what's invisible.

Shedding Infrared Light on Invisible Objects

Sometimes archaeologists hunt for specific light waves, for example. Infrared light is not normally visible to humans. But vegetation can be clearly seen with infrared light. So archaeologists use special light filters that make infrared visible.

It can also be helpful to measure heat or changes in temperature, as a team of archaeologists recently found out when researching a well-known site in New Mexico, United States. The ruins left in Chaco Canyon by the Anasazi people have been studied for decades. But with the help of a special scanner to detect different temperatures at ground level, the team found something that had never been recorded: a network of ancient roads.

Archaeologists can also use laser beams to detect what's hidden. With the help of an airplane or satellite, archaeologists can project a laser beam onto Earth's surface and measures the time it takes for the laser's light to return. By plotting these measurements onto a map, archaeologists can identify lines in the ground that are normally impossible to distinguish.

NASA, the U.S. space agency, once tried this method using the space shuttle and radar. As the shuttle circled Earth, it bounced radar waves over a region in northern Africa. The experiment revealed lines in the Sahara desert that were carved by ancient rivers. Scientists believe these ancient waterways may help explain the bending path of the Nile River.

Ground-Penetrating Radar Creates 3-D Image

There is another type of radar system that is used closer to the ground. When archaeologists use ground-penetrating radar (GPR), they shoot energy pulses into the ground and measure the returning echo. That can tell them if an object is present and just how deep it's buried. Archaeologists often use GPR to create a three-dimensional picture of what's hiding beneath them.

Images like these provide valuable information to archaeologists long before they embark on a full-scale archaeological dig. Without this information, archaeologists can only make educated guesses about where to begin exploring. But with a picture to guide them, they can figure out the best approach in advance.

This was particularly helpful to a team of archaeologists working in Israel in 2012. As they created a three-dimensional view of a buried city, they spotted an ancient cave filled with jars. Knowing exactly where the cave was located meant they could excavate the jars without disturbing artifacts nearby.

Once a site has been surveyed, it can be excavated and the artifacts removed for closer study. Modern chemistry offers various ways to identify an artifact's important properties, like age and makeup. In the past, this type of information was left largely to guesswork.

Thanks to science and technology, today's archaeologists rarely guess anymore. Just as they rarely sift aimlessly through dirt, hoping to get lucky.