Question

Explain why the first observed rising of the bright star Sirius in the sky just before dawn happens at the same time each year. How did ancient Egyptians take advantage of this?

Answer 1

Explain why the first observed rising of the bright star Sirius in the sky just before dawn happens at the same time each year. How did ancient Egyptians take advantage of this?

The brightest star visible from any part of Earth is Sirius in the constellation Canis Major the Greater Dog. Sirius is sometimes called the Dog Star. Every year it first appears in the eastern sky of Cairo on the morning of August 5just before dawn. After this date, It can be seen 4 minutes earlier each day, climbs about 1 degree higher each day, and remains visible for longer period in the pre-dawn hours. This continues until Sirius can no longer be seen after it sets on the early evening of May 26 the next year. However, about 2 months later on august 5, Sirius comes back into view again before sunrise. Because of this precise pattern of appearance and disappearance. The varying density and temperature of Earth’s air affect starlight, especially when we’re seeing the star low in the sky. The heliacal rising is the first rising of a star (or a planet, a constellation, or the Moon) over the eastern horizon just before sunrise after a period when the star had not been visible. Every day after the heliacal rising, the star rises a bit earlier and is visible for a little longer before dawn.

In ancient Egypt, the name Sirius signified its nature as scorching or sparkling. The star was associated with the Egyptian gods Osiris, Sopdet and other gods. Ancient Egyptians noted that Sirius rose just before the sun each year immediately prior to the annual flooding of the Nile River. Although the floods could bring destruction, they also brought new soil and new life. Osiris was an Egyptian god of life, death, fertility and rebirth of plant life along the Nile. Sopdet – who might have an even closer association with the star Sirius – began as an agricultural deity in Egypt, also closely associated with the Nile. The Egyptian New Year was celebrated with a festival known as The Coming of Sopdet.