# How is Mount Everest’s Height Measured?

Have you ever wondered how the world’s highest mountaintop’s elevation, Mount Everest, is ascertained? The measurement of Mount Everest’s height involves complex geological and surveying procedures. This article aims to shed light on the methods used by surveyors and geologists to accurately measure the height of Mount Everest.

## A Historical Approach

In the early 19th century, when scholars began attempting to measure the height of Mount Everest, they employed rudimentary trigonometry. At first, they would set up a series of connected triangles from a baseline whose length they had measured. By precisely measuring the angles of the triangle, they could calculate the height of the distant mountain.

The Great Trigonometrical Survey of India in 1856 initiated this process under the leadership of Sir George Everest, the Surveyor General of India, after whom the mountain was later named. Using this method, the Survey of India recorded the first known height of Mount Everest as 29,002 feet. However, this antiquated method involved complex calculations and immense groundwork, and more precise techniques evolved with time.

## Modern Measurement Methods

Modern surveyors use advanced technology like GPS and RADAR, which have increased the accuracy levels of the measurements.

### Global Positioning System (GPS)

GPS receivers can be placed at the summit of Mount Everest to gather and transmit data to various satellites orbiting our planet. The distance can be calculated using the delay between the time a signal is sent by a satellite and when it is received by the GPS unit. By knowing the travel speed of the signal and the time delay, we can calculate the distance.

RADAR (Radio Detection and Ranging) technology sends high-frequency radio waves and then captures their reflected signals. This technology is used to scan the topography of the highest peak and understand the rock-ice ratio, which indirectly helps in calculating the actual height of the summit.

#### Light Detection and Ranging (LiDAR)

LiDAR technology, similar to RADAR, uses light from a laser instead of radio waves to measure distances.

Despite the advancements in measurement technologies, even slight inaccuracies can make a significant difference at such great heights, leading to variations in the reported elevations.

### Consideration of Tectonic Forces

Mount Everest is situated in the Himalayan range, where the Indo-Australian Plate is forced under the Eurasian Plate due to tectonic activity. This movement results in the mountain’s height changing constantly, albeit by tiny amounts each year.

Therefore, geologists and scientists need to frequently re-measure Mount Everest to record an accurate height.

# FAQs

1.

#### How often is Mount Everest’s height measured?

The mountain’s height isn’t measured regularly due to the difficulty and danger associated with such measurements. The last comprehensive survey was conducted by China and Nepal in 2020, and before that, India conducted a measurement exercise in 1955.

2.

#### Has the height of Mount Everest changed over time?

Due to the ongoing tectonic activity, the elevation of Mount Everest increases slightly each year. However, natural disasters like earthquakes can also affect it. The 7.8-magnitude earthquake in April 2015 in Nepal is believed to have changed the mountain’s height.

3.

#### What are the challenges in measuring Mount Everest’s height?

Extreme weather conditions, the risk of avalanches, low oxygen levels, and high-altitude sicknesses are just a few of the perils that make it dangerous for surveying teams. Furthermore, the measurement equipment itself must be engineered to withstand these harsh conditions.

4.

#### Does the measurement include the snow cap?

Yes, the official measurements include the snow cap. The recent 2020 survey by China and Nepal measured both the rock height and the snow height. The snow height is now recognized as the official height.

5.

#### Why is GPS technology not enough to measure the height accurately?

Although GPS technology is considered accurate, it does have its limitations. It doesn’t account for factors like gravitational pull, which can vary at different spots on Earth and thus influence the measurements. Therefore, various methods and corrections are applied to get the most accurate measurement.