On 30 June 1908, a farmer in central Siberia saw a raging forest fire. He heard sounds like cannons. The blast knocked down about 80 million trees over an area of 2150 km². This incident is known as the Tunguska event.
Scientists debated for many years about what could have caused this event. In 2013, fragments from the Tunguska site were found and analysed. Scientists think that the incident was caused by a comet. Comets are made of rock and ice. Although a comet is smaller than an asteroid, it could strike Earth at high speeds and so cause much more damage than a larger asteroid.
The comet involved in the Tunguska event was captured in the Earth–Moon system and remained in Earth's orbit for a long time. It gradually broke into pieces and caused unusual twilights over northern Europe between 25 June and 1 July in 1908.
Research and list the primary and secondary sources of information about the Tunguska event.
| Primary sources of information | Secondary sources of information |
|---|---|
| | |
On 30 June 1908, a farmer in central Siberia saw a raging forest fire. He heard sounds like cannons. The blast knocked down about 80 million trees over an area of 2150 km². This incident is known as the Tunguska event.
Scientists debated for many years about what could have caused this event. In 2013, fragments from the Tunguska site were found and analysed. Scientists think that the incident was caused by a comet. Comets are made of rock and ice. Although a comet is smaller than an asteroid, it could strike Earth at high speeds and so cause much more damage than a larger asteroid.
The comet involved in the Tunguska event was captured in the Earth–Moon system and remained in Earth's orbit for a long time. It gradually broke into pieces and caused unusual twilights over northern Europe between 25 June and 1 July in 1908.
What do scientists now think about the cause of the Tunguska event? What supported their belief?
The Moon's core is much smaller than Earth's. It contains a mixture of iron with small amounts of sulfur and nickel. The Moon's mantle is rich in iron and magnesium. Its crust is covered with a layer of regolith. Regolith is a type of dust that was formed from asteroids, comets and meteors hitting the Moon for billions of years. On the surface of the Moon are large plains known as maria. They were created by ancient volcanic activities. There are also highlands and many craters. The back of the Moon, the part that is not visible from Earth, has many more craters.
Work in groups. View images of Earth, Theia and the Moon. Choose one to model.
Choose a polystyrene foam ball or modelling clay as the base material for your model.
Choose appropriate materials to show the different compositions and physical features of
a. young Earth and Theia;
b. young Earth and Theia during collision;
c. Earth and the Moon after collision.
List any additional materials you will need.
Use the image to guide your design and surface features to make your model more accurate and realistic. Polystyrene foam balls are lightweight and easy to work with, while clay allows for more sculpting and detailing.
You are making a model of young Earth and Theia colliding and of Earth and the Moon after the collision, using a polystyrene foam ball or modelling clay and art supplies.
Assess any safety risks and write the necessary safety precautions.
You are making a model of young Earth and Theia colliding and of Earth and the Moon after the collision, using a polystyrene foam ball or modelling clay and art supplies.
Present your models to another group and ask for feedback. Write the strengths and limitations of your model in this table.
You are making a model of young Earth and Theia colliding and of Earth and the Moon after the collision, using a polystyrene foam ball or modelling clay and art supplies.
Based on the feedback, how could you improve your model?
Scientists once believed that the Moon formed through the capture of a large object by Earth’s gravity. Later, the collision theory was proposed, which suggests that the Moon formed from debris after a collision between Earth and another celestial body.
Try to observe one of the nebulae visible to the naked eye or through a telescope, such as the Orion Nebula. What type of evidence are you trying to collect?
You have tried to observe a nebula, such as the Orion Nebula, with the naked eye or a telescope. Compare your observation with the information from the secondary sources. If this is not possible because you are not able to make the observation, proceed to the next question.
You are investigating a nebula such as the Orion Nebula. If direct observation is not possible (due to weather, location or lack of equipment), reflect on how such experiences might differ from secondary sources.
For this scenario, decide whether you would use first-hand experience and/or secondary sources. Explain your decision.
You are an amateur astronomer writing a blog post about the Carina Nebula. You want to include personal observations. However, the nebula is too far south to be visible from your location, and you lack access to larger observatories.
