Approximately how long ago did the sun form? 4.5 million years ago 4,000 years ago 4.5 billion years ago none of these are correct

4.5 billion years ago

Explanation:

The sun formed about 4.57 billion (4.567 billion) years ago when a molecular cloud collapsed. Some physical models indicate that the star gets up to 10 percent brighter every billion years, so today's sun is about 40 percent brighter than it was at the time of its creation.

The future of the sun will be marked by the moment when all its hydrogen is converted to helium. When this occurs, it will be increased in size by up to 200 times, and may reach the orbit of Venus.

At the end of its life, the Sun will suffer a huge gravitational collapse, its size will be reduced until it becomes a dwarf white star. Astronomers estimate that at this stage the sun will be about 50 percent of its current mass and that its size will be comparable to that of Earth.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.