The mighty river featured in this image is called the Yarlung Tsangpo as it courses through the Tibetan Autonomous Region of China, and is then known as the Dikrong during its passage through India's state of Arunachal Pradesh. Further downstream, the river widens and becomes the Brahmaputra. Its waters eventually empty to the Bay of Bengal.

The answers to this quiz appear in blue below each question.

1. Within the image area, the river flows across an international boundary into an area where over 100 species of orchids grow.

Answer: TRUE
The verdant green hues present in the lower right image corner are characteristic of Arunachal's lush vegetation, which includes over 400 types of orchid.

2. The river's name in a particular language means "pacifier" in English.

Answer: FALSE
The translation of the name "Tsangpo" is "purifier". Although the river has at least three names from as many languages, there is no indication that the river's name means "pacifier" in any language.

3. Sedimentary rocks containing mineral grains that record changes in the orientation of Earth's magnetic field have been found north of the river.

Answer: TRUE
Sandstone containing grains of magnetic minerals that record the alternating pattern of the Earth's magnetic field have been found north of the river, near the Tibetan capital of Lhasa.

4. At least one expert kayaker has perished attempting to navigate a deep gorge of the river.

Answer: TRUE
A Japanese expedition attempted to navigate the river in 1993, but lost one member of their team in the gorge near Namche Barwa peak, and the American team sponsored by the National Geographic Society in 1998 had to turn back after their most experienced kayaker was lost along the same stretch of the river.

5. The two highest named peaks within the image area are situated on opposite sides of the river; each has a maximum elevation of nearly 4000 meters.

Answer: FALSE
The Yarlung Tsangpo is the highest major river in the world, with an average elevation of about 4000 meters. At least two peaks within the image area rise to over 7000 meters: Namche Barwa at 7756 meters and Gyala Peri at 7150 meters.

6. The description of a mythical place in a 1930's British novel is thought by some explorers to have been inspired by a location on this river.

Answer: TRUE
The myth of Shangri-la, as described in James Hilton's 1933 novel "Lost Horizons", is believed by a number of explorers to have been geographically inspired by the deepest gorges and waterfalls of the Tsangpo.

7. Scientists believe that 100 million years ago the region through which the river flows was farther from the equator than it is today.

Answer: FALSE
One hundred million years ago, the Indian subcontinent is thought to have been located thousands of kilometers closer to the equator. Geological evidence points to the collision of the subcontinent with Asia about 40-50 million years ago. The impact slowed the northward movement and led to the formation of the Himalayas.

8. In the 1920's, an expedition along the river searched for and successfully encountered a legendary 30-meter-high waterfall.

Answer: FALSE
A 30-meter (100-foot) waterfall had been reported by Kintup, an illiterate tailor from Sikkim who explored the Tsangpo for several years in the 1880's. However, the expedition led by Frank Kingdon-Ward in the 1920's discovered only a 21-meter (70-foot) waterfall (Rainbow Falls). The legendary 30-meter falls was not re-discovered until 1998.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.