Variable stars are characterized by their changing brightness, which can be caused by various factors such as pulsations, eclipses, or changes in the star's structure.

Cepheid variables are a type of pulsating variable star that exhibits regular and predictable changes in brightness. They are important in astronomy for their use in determining distances to other stars and galaxies.

Novae are sudden and dramatic outbursts of brightness in a star, caused by a thermonuclear runaway on its surface. They are often associated with binary star systems.

Mira variables are a type of long-period variable star that exhibit slow and regular changes in brightness. They are named after the star Mira, which is a well-known example of this type of variable star.

A binary star is a system of two stars that orbit around a common center of mass. They are often studied in astronomy to understand stellar evolution and interactions.

The transit method is a widely used technique for detecting exoplanets. It involves observing a star for periodic dips in brightness caused by an exoplanet passing in front of it.

An exoplanet is a planet that orbits a star outside our solar system. The study of exoplanets is a rapidly growing field in astronomy, as it helps us understand the diversity of planetary systems in the universe.

Gas giants are large exoplanets primarily composed of gases such as hydrogen and helium. They are often several times larger than Jupiter and have low densities.

Super-Earths are exoplanets that are larger than Earth but smaller than gas giants. They are typically rocky or icy in composition and may have atmospheres.

Hot Jupiters are exoplanets that are similar in size to Jupiter but orbit very close to their host stars. They have high surface temperatures due to the intense radiation they receive.

Ocean planets are exoplanets that are primarily composed of water. They may have thick layers of ice on their surfaces and are thought to be common in the universe.

Terrestrial planets are exoplanets that are primarily composed of rock or metal. They are similar in composition to Earth and may have atmospheres.

Rogue planets are planets that are not bound to any star and roam freely through space. They are difficult to detect and study due to their lack of a host star.

Gas giants are large exoplanets primarily composed of gases such as hydrogen and helium. They often have thick atmospheres and may have multiple moons orbiting them.

Dwarf planets are small celestial bodies that are smaller than planets but larger than asteroids. They are typically rocky or icy in composition and may have atmospheres.