Earth in Space

Front

What are nebulae?

Back

Giant clouds of gas and dust where stars begin, also known as star nurseries.

Front

What happens in a nebula to form a star?

Back

Gravity pulls gas and dust together into clumps, forming a dense and hot center called a protostar.

Front

What is a protostar?

Back

A hot, dense center formed in a nebula where nuclear fusion has not yet started.

Front

When does nuclear fusion start in a star?

Back

When the core of a protostar reaches a very high temperature, hydrogen atoms join to make helium atoms, releasing a lot of energy.

Front

What is a main sequence star?

Back

A star that begins to shine and has a stable balance of forces after nuclear fusion starts.

Front

How did our Sun form?

Back

Our Sun formed about 4.6 billion years ago from the solar nebula.

Front

What are the stages of star formation?

Back

1. Nebula, 2. Gravity pulls matter into clumps, 3. Protostar, 4. Nuclear fusion starts, 5. Main sequence.

Front

What causes day and night on Earth?

Back

Earth rotates on its axis, causing different parts to experience sunlight (day) and darkness (night).

Front

What defines a year on Earth?

Back

A complete orbit around the Sun, taking about 365.25 days.

Front

What are stars?

Back

Massive burning balls of hydrogen gas where hydrogen is converted to helium through nuclear fusion, releasing heat and light.