Astrophysics and Celestial Measurements Quiz

Astronomy that studies the behaviour and physical properties of celestial objects using mathematical models.

The standard unit of measurement in astronomy, equal to the average distance between the Earth and the Sun.

A technique to measure the distances to stars, based on the apparent shift in their positions when viewed from different points in Earth's orbit.

Nebulae composed of ionized gas that emit light due to the excitation of their atoms, often a vibrant colour.

Nebulae that reflect light from nearby stars, usually appearing blue because of the colour of the reflected light.

A change in the observed wavelength of light due to the motion of the emitting object; blueshifted indicates an object moving towards us.

A star that exhibits regular, periodic variations in its brightness over time due to internal processes.

A dense cloud of gas and dust that blocks light from stars behind it, often appearing as dark patches against a brighter background.

The Big Bang theory suggests that the universe began as a singularity that expanded rapidly, while the Steady State theory proposed a universe that is infinite and unchanging, with new matter constantly being created to maintain a consistent density.

Dark matter interacts gravitationally with other matter but does not emit or absorb light, making it invisible to telescopes. Dark energy is a mysterious force causing the accelerated expansion of the universe.

Apparent magnitude refers to how bright a star appears from Earth, while absolute magnitude represents its true intrinsic brightness, as if it were located 10 parsecs away.

A star with a larger absolute magnitude is further away from Earth because its apparent magnitude (brightness as seen from Earth) is significantly dimmer compared to its absolute magnitude (true brightness).

Absorption spectra are produced when light from a hot object passes through a cooler gas, resulting in dark lines in the continuous spectrum. This happens when atoms in the gas absorb specific wavelengths of light.

Wien's Law describes the relationship between the maximum wavelength of radiation emitted by a blackbody and its temperature. It states that the wavelength at which the peak of the radiation occurs is inversely proportional to the object's temperature.

Absorption lines in a star's spectrum occur when certain wavelengths of light are absorbed by atoms in the star's atmosphere. These absorbed wavelengths correspond to specific energy levels within the atoms, creating dark lines in the otherwise continuous spectrum.

A main sequence star is in a stable state because the outward pressure from the heat generated by nuclear fusion in its core is balanced by the inward pressure of gravity.

An open universe is one where the density of matter is less than the critical density, meaning that gravity is not strong enough to halt the expansion of the universe. The universe will expand forever.

M class stars are the coolest stars, with surface temperatures ranging from 2,400 to 3,700 Kelvin. Their red colour is due to their relatively low temperature, which causes them to emit more red light than other colours.

The Stefan-Boltzmann Law states that the total energy radiated by a blackbody per unit area is proportional to the fourth power of its absolute temperature. This means that hotter objects radiate much more energy than cooler objects.

Galaxies formed during the structure formation stage of the Big Bang, which occurred after the early universe had cooled and expanded significantly. The formation of galaxies involves the gravitational collapse of matter within the expanding universe.

The final stage for a star with the mass of the Sun is a white dwarf. This is a very dense, hot, and compact remnant of the star's core remaining after its outer layers have been expelled.

Apparent magnitude describes how bright a star appears from Earth. Absolute magnitude represents the star's true intrinsic brightness as if it were located 10 parsecs away.

The distance light travels in one year, a massive distance used to measure vast distances in the universe.

A technique used to measure the distance to stars by observing its apparent shift against the background as Earth orbits the Sun. The closer the star, the greater the shift.

A method of classifying galaxies based on their shape. It is used to distinguish between spiral, elliptical, and irregular galaxies.

A type of star whose brightness changes over time due to internal processes. It is used to measure distances in space as the period of its brightness changes is related to its absolute magnitude.

The universe's outward expansion is accelerating due to a mysterious force called dark energy. It counteracts gravity's pull and drives the universe's expansion.

A type of nebula that glows brightly due to the excitation of its gas atoms, often visible in vibrant colours.

A cloud of gas and dust that absorbs light from behind it, appearing as a dark patch against a brighter background.

Wien's Law describes the relationship between the peak wavelength of radiation emitted by an object and its temperature. It states that hotter objects emit radiation at shorter wavelengths, while cooler objects emit radiation at longer wavelengths.

The Stefan-Boltzmann Law states that the total energy radiated per unit area of a blackbody is proportional to the fourth power of its absolute temperature. This means that hotter objects emit much more energy than cooler objects.

Absorption lines in a star's spectrum are formed when atoms in the star's atmosphere absorb specific wavelengths of light. These absorbed wavelengths correspond to energy levels within the atoms, creating dark lines in the otherwise continuous spectrum.

M class stars are the coolest stars, with surface temperatures ranging from 2,400 to 3,700 Kelvin. Their red color is due to their relatively low temperature, which causes them to emit more red light than other colors.