The Egyptian civilization achieved many scientific and technological innovations. One of these was their calendar. It was based on 365 days, with twelve months and three seasons. Each month had three ten-day-long weeks. The last five days of the year corresponded to the birthdays of the five gods and goddesses: Osiris, Isis, Horus, Seth, and Nephthys. Today, we know that the Egyptians were only ¼ of a day short and that is the reason why we now have a leap year once every four years. The three seasons consisted of four months each. They corresponded to the cycle of the Nile. New Year's day was July 19 (by the Julian calendar) and marked the beginning of the first season called akhet and was the time of the flooding of the Nile. November 16, when the crops began to grow, marked the start of the second season called peret. March 17, or harvest time, was the beginning of the third season, shemu. July 14-18 were the last five days of the year and were considered to be unlucky and dangerous. There was also a religious calendar that marked the festivals and ceremonies dedicated to particular deities and their temples.
The ancient Egyptians studied the sky and the stars carefully. They took measurements to align their pyramids and sun temples to the four cardinal points of the earth. The used a merkhet (similar to an astrolabe) to mark sightings of the Great Bear constellation and the Orion. They used their measurements to build such structures as the Great Pyramids at Giza, whose sides are accurately aligned to face north, east, south, and west. Some historians believe that they also used these measurements to build the Giza plaza as a reflection of the Duat. This was the kingdom of Osiris, located in the region of the sky where the stars Orion and Sirius rise just ahead of the sun at dawn on the summers solstice. The three pyramids would represent the three stars in the belt of Orion, the Sphinx would represent the constellation Leo, and the Nile would correspond to the Milky Way.
Ancient Egyptians also practiced medicine. They believed that if a person got sick it was because of the wrath of a god or an evil spirit. Both priests and doctors were called upon to heal the sick. Egyptian doctors did not understand the functioning of the body. It was believed that the heart, not the brain, was the center of all thinking. They also thought that blood, urine, excrement, and semen circulated around the body. However, even without their full knowledge of the body, the Egyptians did manage to practice mummification that has preserved many mummies to this day.
First, the soft, moist body parts that would cause decay were removed. During, the Old and Middle Kingdoms, the brain was left in the head but, in the New Kingdom it was removed by using a special hook. The stomach, liver, intestines, and lungs were preserved by drying them in a special salt called natron. After drying, these body parts would be placed in a four-chambered box made of wood, clay, or stone. Later, it was customary to place each organ in a separate jar. The stoppers of the jars would be shaped like each of the four sons of Horus and they would protect the organ in the jar. The jars would be placed next to the mummy. The heart which was sometimes left in the body and sometimes taken out, was dried with natron and then put back in the mummy. After the organs were removed, the body was washed with wine that acted as an antiseptic, which killed bacteria. The body would be then rubbed with spices and covered with natron. It was left for 40 days to dry. Once dried, the skin became shrunken and leathery, so it had to be cleaned again and rubbed with oils. The body was then adorned with jewelry, covered with linen shrouds, and bound with linen strips. Small amulets were inserted between the layers of the bandages to protect the mummy's spirit on the way to its afterlife. Some of the amulets were a wedjat (the eye of Horus) which heals the mummy in the afterlife, a tet that protected the limbs, an ankh that was the symbol of life, and a djed column that stood for strength. As the layers layer of bandages were added, they were coated with resin to hold the wrappings together.
special salt called natron. After drying, these body parts would be placed in a four-chambered box made of wood, clay, or stone. Later, it was customary to place each organ in a separate jar. The stoppers of the jars would be shaped like each of the four sons of Horus and they would protect the organ in the jar. The jars would be placed next to the mummy. The heart which was sometimes left in the body and sometimes taken out, was dried with natron and then put back in the mummy. After the organs were removed, the body was washed with wine that acted as an antiseptic, which killed bacteria. The body would be then rubbed with spices and covered with natron. It was left for 40 days to dry. 
Once dried, the skin became shrunken and leathery, so it had to be cleaned again and rubbed with oils. The body was then adorned with jewelry, covered with linen shrouds, and bound with linen strips. Small amulets were inserted between the layers of the bandages to protect the mummy's spirit on the way to its afterlife. Some of the amulets were a wedjat (the eye of Horus) which heals the mummy in the afterlife, a tet that protected the limbs, an ankh that was the symbol of life, and a djed column that stood for strength. As the layers layer of bandages were added, they were coated with resin to hold the wrappings together.