In the night sky: Orion
In the night sky: Orion

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Orion Glossary


Browse the glossary using this index

Special | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL

Page: (Previous)   1  ...  3  4  5  6  7  8  9  10  11  12  (Next)
  ALL

R

red giant

A large, cool star that is going through subsidiary stages of nuclear reactions, having exhausted its hydrogen fuel supply.


red giant branch

A region on the Hertzsprung-Russell diagram in which red giants (luminous but cool stars in the later stages of their evolution) are found.


redshift

A shift of a spectral line to redder (longer) wavelengths. There are two types of redshift discussed in this course: (1) Doppler shift – resulting from motion of the emitting object away from the observer. This is the case for some nearby galaxies, but this is not the underlying physical cause of most cosmological redshifting. (2) Cosmological redshift – resulting from expansion of the Universe (see the Hubble constant, Big Bang) which stretches the wavelength of the light, making the light redder.


rocky materials

Materials, such as minerals and metals, that are present in Solar System bodies that require high temperatures in order to melt (cf. icy materials).


S

satellite

An object in orbit around a larger one, e.g. a ‘moon’, or an artificial space probe orbiting a planet.


silicon burning

The process of silicon burning produces elements such as sulfur, argon and calcium via the fusion of silicon nuclei at the end of the life of a massive star.


size of the observable Universe

That part of the wider Universe that has been able to send us light signals since the beginning of the Universe. The Universe as a whole is larger, perhaps infinitely larger, than the observable part of it.


solar nebula

The hypothetical cloud of gas and dust within which the Sun and other constituents of the Solar System formed.


Solar System

The system comprising the Sun and all the bodies (planets and their satellites, dwarf planets, comets and asteroids) that orbit around it.


spectrum

A display (such as a graph or a photograph) of the distribution of light or other types of radiation versus the wavelength (or frequency or energy) of the radiation. It indicates the intensity of light at each different wavelength. A spectrum may be a continuous spectrum or may show emission lines (emission spectrum) or absorption lines (absorption spectrum).



Page: (Previous)   1  ...  3  4  5  6  7  8  9  10  11  12  (Next)
  ALL


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371