This may be the most important photograph in human history. Earthrise was taken during the Apollo 8 flyby mission in 1968 before the landing of Apollo 11.
For a spinning droplet of water in microgravity, centrifugal forces can direct the higher density fluid towards the outer surface while air bubbles remain along the axis of rotation.
Refraction causes a rigid object to appear fragmented when it is placed in two different optical mediums.
A portion of the salt and pepper you see on an analog television actually comes from the radiation left over from the Big Bang. The radiation, known as the cosmic microwave background, permeates all of space and gives the universe an average temperature of 2.7 K (-455 degrees F), just slightly above absolute zero.
The first detection of the microwave background was made in 1964 at AT&T Bell labs where physicists initially thought that an accumulation of bird droppings on their 20-foot antenna was the source of the unwanted noise signals. The Nobel Prize in Physics was awarded for the accidental discovery which supported the now prevailing Big Bang Theory.
The transfer of Information in any form is limited to the speed of light. If our Sun suddenly disappeared, it would take 8 minutes for the last photon emitted by the Sun to reach Earth; the Earth would be lit for 8 minutes before darkening. What’s even stranger is that the Earth would remain in its orbit and revolve around nothing for the entire 8 minutes! Even gravity can’t travel faster than light.
Iridescence is the apparent change in the color of a surface as its angle of illumination or view changes. Ordinary colors arise from pigments which absorb certain wavelengths of light while reflecting others. Pigmentation depends on the chemical properties of matter.
The bright colors of a butterfly’s wings, on the other hand, depend entirely on its physical structure. Tiny patterns within its wings allow the butterfly to display the iridescent effect and scatter light in fascinating ways.
With the exception of galaxies that are gravitationally bounded in clusters, distant galaxies are receding from each other at ever accelerating rates. On the largest scale of the universe, everything is moving away from everything else; the universe is expanding!
The expansion behaves very similar to an expanding balloon where every point on its surface recedes from all other points. If we reverse the trajectories of galaxies in the universe, much like the rewinding of a firework display, they all trace back to an origin where everything was initially clumped together.This point is referred to as the Big Bang.
Because of the tremendous sizes of galaxies and the vast distances that separates each one, the collisions between two galaxies often take billions of years to complete. We know of such events because we can observe the collisions of other galaxies in progress.
The Andromeda Galaxy, our nearest neighbor located 2.5 million light-years from the Milky Way Galaxy, is currently on a collision course with us. The cosmic train wreck is expected to begin in about 4 billion years. Luckily, it is unlikely that any star, including our Sun, will be affected because even the stars are separated by huge distances within each galaxy.
By the law of buoyancy, helium can lift balloons because helium gases weigh less than the nitrogen and oxygen gases in our atmosphere. Most helium filled balloons will pop as they rise to high altitudes where the air pressure is lower. As the balloons pop, the gases continue to rise until they escape into outer space. This begs the question of where helium comes from if every helium atom tends to rise until it is forever lost by the Earth.
Deep within the Earth’s mantle, heavy elements such as Uranium undergoes nuclear fission by radioactive decay. Not only does this process release heat to warm the Earth from within, it also releases helium! The gases remain trapped in underground pockets until they are collected.