A Universe Painted in Light.
Imagine the universe as a vast canvas, where every celestial object is a brushstroke of color revealing hidden stories. Unlike your usual paintings, the pigments don’t decide the hues, but the light does! The colors of the universe tell us a lot about a star’s temperature, the chemical composition of a planet’s atmosphere, the distance between Earth and a particular celestial object, the movement of distant galaxies, etc.
Why do Planets and Stars Wear Their Colors?
Stars reveal their temperatures through color. Scorching hot stars blaze blue, cooler ones glow orange, and the coolest twinkle red. These colors serve as cosmic thermometers, telling us the age and life stage of a star.
Coming to the planets, Mercury ’s high iron content is responsible for its slat grey color. Our twisted twin, Venus appears pearly white (thanks to the sulphuric acid clouds!) with a yellowish tinge. Mars, the butterscotch planet, looks reddish-brown because it is covered in dust with high iron content that gets oxidized (Fe2O3) and the Martian winds can kick up global dust storms giving it a reddish hue. Coming to the “Great Red Spot” of Jupiter which is considered one of the oldest and deadliest storms of the solar system; is at a higher altitude than the rest of Jupiter’s atmosphere and hence the trace chemicals in the clouds- ammonia and acetylene get a bigger dose of radiation giving it that characteristic red color. The blue brothers, Uranus and Neptune have a higher proportion of methane and the majority of their masses are due to ices like water, methane, and ammonia paired up with less haze in their atmosphere giving them their placid, opaque blue appearance.
When Colors Reveal Motion: The Doppler Effect.
Have you ever noticed how an ambulance siren sounds higher-pitched when it approaches and lower when it moves away? Light behaves the same way. When the galaxies (source of waves-visible light) move towards you, the wavelength decreases and shifts towards the blue end of the spectrum- blueshift. When they move away, the wavelength increases and shifts towards the red end of the spectrum- redshift. The greater the motion toward or away from us, the greater the Doppler shift. However, the Doppler shift doesn’t “change” the pattern of lines from an element present in a celestial object; rather it just shifts the whole pattern slightly, and hence astronomers can still decode the elemental composition.
The Mysteries Hidden in Cosmic Colors of Nebulae.
We can agree that nebulae are some of the most majestic-looking objects in the universe. They are giant clouds of gas and dust in space and their colors are not just for show, they reveal the chemistry and physics happening inside them. The Pillars of Creation in the Eagle Nebula are dense columns of gas where new stars are forming. Their eerie glow is a mix of hydrogen (green), sulfur (red), oxygen (blue) and nitrogen (green). The NGC 248 is a glowing pink nebula. Intense radiation from the central stars heats up and ionizes the hydrogen (H-alpha) giving it that reddish-pink hue.
The Future of Cosmic Color Exploration.
Every shade in the universe’s palette tells a story. With upcoming telescopes like the James Webb Space Telescope, we’re poised to see even deeper into the universe’s past, unveiling colors and chemical signatures we’ve never witnessed before.
The next time you gaze at a sunset’s fiery hues or the cool blue of a twilight sky, remember you’re witnessing the same physics that paints the cosmos and we’re just beginning to understand its brilliance. References:
-By Ketki Patil
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