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Red shift occurs when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum. This can often be observed in light from distant galaxies, indicating they are moving away from us.

A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 29 solar masses. Neutron stars are extremely dense and can be observed when they emit radiation, often as a pulsar or due to accretion from a companion star.

A comet is an icy small Solar System body that, when passing close to the Sun, warms and begins to release gases. This process, called outgassing, creates a visible atmosphere or a tail. Comets can be observed usually when they are near the Sun.

A blue moon is a phenomenon where a full moon appears twice in one calendar month, or the third full moon in a season with four full moons. Despite the name, the moon doesn't actually appear blue and can be observed in the night sky similar to regular full moons.

Auroras are natural light displays in the Earth's sky, typically seen in high-latitude regions. They result from the collision between the Earth's atmosphere and charged particles from the sun. Auroras can be observed at night, usually near polar regions.

Transit is an astronomical event that occurs when one celestial body passes directly in front of another, from the perspective of the observer. This can be commonly observed with Mercury and Venus passing in front of the Sun.

A quasar is a highly luminous object powered by a supermassive black hole at its center, visible from great distances. Quasars are observed in the distant universe and are important in understanding the early universe.

A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape from it. The presence of black holes can be inferred from the motion of other stars close to it or when matter is being pulled into it.

The solar wind is a stream of charged particles (plasma) released from the upper atmosphere of the Sun. This phenomenon can lead to auroras and has effects on space weather. It can be detected indirectly via spacecraft.

The CMB radiation is a thermal radiation left over from the time of recombination in Big Bang cosmology, approximately 380,000 years after the Big Bang. It can be observed with sensitive radio telescopes nearly uniformly from all directions.

An eclipse occurs when one astronomical body moves into the shadow of another or when an object passes in front of another, as with a solar or lunar eclipse. Solar eclipses can be observed during the daytime, while lunar eclipses are visible at night.

A supernova is the explosion of a star, occurring at the end of its lifecycle when it runs out of nuclear fuel. It can be observed when a previously undetected star becomes extremely bright before gradually fading away.

Hubble's Law describes the observation that the farther away a galaxy is, the faster it is moving away from us. This relation is given by $v = H_0 imes d$, where $v$ is the galaxy's velocity, $H_0$ is Hubble's constant and $d$ is the distance to the galaxy.

A pulsar is a highly magnetized rotating neutron star that emits beams of electromagnetic radiation out of its magnetic poles. This radiation can only be detected when a beam is pointing toward Earth, observed as pulses of radiation.