Ancient Observatories (Pt 2): Observatories

Summary

The video explores ancient astronomical practices and timekeeping methods, highlighting early observatories like Stonehenge and the use of markers, circles, and temples to track celestial events. It discusses how the Egyptians created a 365-day solar calendar and how the Greeks developed the gnomon for shadow tracking. The Navajo culture's use of sun shadows for timekeeping is also featured, along with a hands-on student activity to observe shadow changes throughout the day. This fusion of historical and modern techniques demonstrates the enduring human connection to the sun and celestial movements.

Takeaways

• 😀 Early observatories included simple markers, stone and wood circles, and temples used to align with the sun during equinoxes and solstices.
• 😀 Stonehenge in England is one of the earliest examples of an observatory, serving as a large calendar for predicting equinoxes and solstices.
• 😀 Ancient Egyptians developed a 365-day solar calendar, synchronized with the helical rising of the star Sirius and the summer solstice.
• 😀 The alignment of statues at Abu Simbel in Egypt allowed sunlight to illuminate the statue of Ramses the Great on October 18th, marking the start of the Egyptian civil year.
• 😀 The Greeks created the gnomon, a portable tool used to track the sun’s movements by measuring its shadow at different times of the day.
• 😀 The length of a shadow depends on latitude, with shorter shadows at the summer solstice and longer ones at the winter solstice.
• 😀 At the equator, shadows disappear during the equinox, and their direction changes with the seasons.
• 😀 The Greek gnomon helped in determining time based on the sun’s position and shadow length, which varied by the time of year.
• 😀 The gnomon was also used to create sundials and track seasonal changes by observing the movement of the sun’s shadow.
• 😀 The activity encourages students to create sun shadow plots, helping them track the sun’s movement and understand how the Earth’s position affects shadow patterns.

Q & A

What were the primary types of early observatories used by ancient civilizations?

Ancient civilizations used three main types of early observatories: simple markers, circles of stone and wood, and temples. These were designed to align with celestial events such as the Equinox and Solstice, marking significant moments in the sun’s movement.

How did Stonehenge function as an early observatory?

Stonehenge, built around 3000 BC in England, functioned as a large calendar. Its stone arrangement was designed to predict equinoxes and solstices by aligning with the sun’s path on these important dates.

What role did the heliacal rising of the star Sirius play in ancient Egyptian astronomy?

The heliacal rising of the star Sirius, which occurred around the time of the summer solstice, was critical for the ancient Egyptians. It marked the start of their solar calendar and coincided with the annual flooding of the Nile, helping them predict agricultural cycles.

What is significant about the alignment of the Abu Simbel temple?

At Abu Simbel, the massive statues of Ramses the Great face east to greet the sun. The temple's inner sanctuary is aligned in such a way that on October 18th, sunlight illuminates a statue of Ramses, symbolizing the start of the Egyptian civil year.

How did the Greeks contribute to early astronomical tools?

The ancient Greeks created the gnomon, a simple stick used to track the sun’s shadow. This device helped people measure the length and angle of the shadow to determine the time of year and was a precursor to the sundial.

How does the length and direction of shadows change during the solstices and equinoxes?

During the summer solstice, the shadow is shortest, and during the winter solstice, it is the longest. At the equinoxes, the shadow is of equal length to those at the solstices, and this pattern is influenced by latitude. At the equator, the shadow disappears at noon during the equinox.

How do the sun's shadow patterns differ between the Northern and Southern Hemispheres?

In the Northern Hemisphere, the summer solstice casts a shadow in a southern direction, while in the Southern Hemisphere, the shadow direction is reversed. This is due to the opposite seasons in each hemisphere.

What is the role of the sun's shadow in Navajo culture, as demonstrated by students in New Mexico?

In Navajo culture, the sun’s shadow is still used to track time and seasons. For example, traditional shepherds rely on the shadow to know when to corral sheep or plant crops, and students from Nukem Elementary School demonstrate this by creating sun shadow plots.

What is the hands-on activity involving gnomons that students at Nukem Elementary School participated in?

Students at Nukem Elementary School created sun shadow plots using gnomons. They tracked the sun’s shadow every half hour throughout the day, analyzed the data by measuring angles and shadow lengths, and learned about the position of the sun at different times of the day.

What educational resources are available for students to further explore the gnomon activity?

An educator guide for the gnomon activity can be downloaded from the NASA Connect website. This guide provides detailed instructions for the hands-on activity, along with a list of materials needed to create and analyze sun shadow plots.