# Astronomical Investigation to Verify the Calendar Theory of the Nasca Lines
## 1 Introduction  
The coastal area in western South America from Patagonia to Ecuador is one of the driest regions on Earth. The cold Humboldt Current in the Pacific prevents cloud formation over the ocean, which means that there is almost no precipitation in this subtropical coastal zone. The only basis for human life is the valley oases of the rivers, which, during the rainy season in the Andes, lead water towards the Pacific for a few weeks per year. In these river oases on the coast of South America, several pre-Columbian cultures developed over the centuries. Nowadays, most people only know the Inca Empire. Although the Inca Empire was the largest in terms of territory, it only existed for a relatively short time before it was conquered by the Spaniards in 1532. However, there were already many important pre-Columbian cultures before the Incas which created impressive structures and cultural assets. One of these cultural heritage sites is located around 450 km south of the Peruvian capital Lima, in the middle of the coastal desert (compare Figure 1)--the geoglyphs at the Pampa of Nasca and Palpa. The geoglyphs are some of the most fascinating and mysterious archaeological sites in the world. Several hundred square kilometers of rock-strewn desert are covered with thousands of lines, large biomorphic figures and various geometric shapes (Figure 2). The drawings vary in complexity. Hundreds of them are simple straight lines, running up to twelve kilometers straight through the desert. However, there are also meandering and zigzagging lines. There are huge areas--mostly triangles and trapezoids--that look like landing strips. Lines and areas often meet in so-called line centers, sometimes situated on slightly elevated places. Between all these lines and areas, numerous figures can be found. There are anthropomorphic figures, zoomorphic designs (such as birds, fishes, llamas, a spider or a monkey), plants (such as trees or flowers) and geometric shapes, e.g., different kinds of spirals. Some of the figures measure more than 300 m in length. That is why the beauty and magnitude of the giant figures can be recognized only from the air [2]. These geoglyphs represent an aritstry of a special kind, neither carved nor painted. They were caused by removing the darker, oxidized layer of the desert's surface to expose the lighter, unoxidized sub-soil below. However, the geoglyphs certainly did not arise all at once; many of them overlap, with the oldest drawings being almost invisible. Most of these geoglyphs have their seeds in the pre-Columbian Nasca culture (approximately 200 BC-650 AC). Only a few, predominantly anthropomorphic representations have their origin in the older Paracas culture (800-200 BC) [3]. Figure 1: Peru—overview map (Reprinted with permission from ref. [1]. 2006 [PERSON]). The fact that these mysterious drawings have remained intact for so many centuries is due to the geographic and climatic situation on the Peruvian coast. The so-far unsolved question is why the people of the Nasca period created these drawings. The mysteries surrounding the Nasca geoglyphs are almost as fascinating as the spectacular drawings themselves. When Dr. [PERSON], professor of history at the Long Island University, saw the Sun setting exactly over a narrow line in the desert of Nasca on 21 December 1941 (see Figure 3), the day of the summer solstice, he concluded that the Pompa of Nasca is \"The Largest Astronomy Book in the World\". The Dresden-born teacher Dr. [PERSON] followed his ideas, and she found many lines, areas and figures that provide evidence for an astronomical orientation. As [PERSON] researched the lines for more than 40 years, she became known as the [PERSON] [4]. The first seemingly systematic astronomical approach was conducted by [PERSON] in 1969. He investigated only a few lines within a very small area compared to  
Figure 3: Astronomical orientation of one of the lines—Sun setting on 21 December 1941 (Reprinted with permission from ref. [4], 1989 [PERSON]).