If you could watch a star falling into a black hole, how would the color of the star change as it approached the event horizon?

A black hole is a region in space where the gravitational pull is so strong that not even light can escape from it.
The boundary surrounding this region is called the 'event horizon'. The event horizon is significant because, once something crosses it, there's no turning back.

As objects, like stars, get closer to this boundary, the gravitational forces become more and more intense.
Imagine a star moving towards this point. The closer it gets, the stronger the gravity it experiences.
This intense gravitational pull affects the light emitted from the star, causing it to change.
The concept of the event horizon is essential for understanding the effects on light, such as the gravitational redshift, which we'll explore next.

When a star falls toward a black hole, it undergoes a noticeable color change due to the process called gravitational redshift.
Here's a simplified understanding of what happens:

• Stars emit light of various wavelengths, which our eyes perceive as different colors
• As the star gets closer to the black hole's event horizon, the gravitational field intensifies
• This strong gravity stretches the light waves, making their wavelengths longer
• Longer wavelengths mean a shift towards the red end of the light spectrum

This shift is why we say the star's light becomes redder as it approaches the black hole.
This phenomenon can go so far that, the closer the star is to the event horizon, the redder it appears, until it potentially becomes invisible.

Light travels in waves, and the wavelength of light determines its color.
In simple terms: shorter wavelengths correspond to blue or violet light, while longer wavelengths correspond to red light.

Gravitational redshift is an important concept related to the wavelength of light.
Here's how it works:

• When light moves away from a strong gravitational field, its wavelength increases, or 'redshifts'
• This means the light stretches out and shifts towards the red part of the spectrum
• The greater the gravitational pull, the more significant this redshift becomes

In the context of stars falling into black holes, the star's light experiences this redshift due to the black hole's powerful gravitational field.
This is why, as the star gets closer to the black hole's event horizon, its light appears redder to an outside observer.