A projection radiograph of the chest: Chest X-rays are commonly used to detect abnormalities in the lungs, but it can also detect abnormalities in the heart, aorta, and the bones of the thoracic area.

Nuclear and subatomic particles moving through space at high speeds: Cosmic rays are radiated from the Sun and other stars.

Cosmic rays are streams of ionizing radiations from space, largely of protons, alpha particles, and other atomic nuclei.

Cosmic rays are very high energy nuclei moving at velocities close to that of light which are probably produced by supernova explosions.

On striking the Earth's atmosphere, they produce cascades of other particles (by collision with nuclei in the atmosphere) called air showers.

Electromagnetic radiation image: A roentgenogram is used in diagnostic imaging to view shadows of tissue density in the body.

In astronomy, any of a class of cosmic objects that emit radiation at X-ray wavelength: Because the Earth’s atmosphere absorbs X-rays very efficiently, X-ray telescopes and detectors must be carried high above it by spacecraft to observe objects that produce such electromagnetic radiation.

Advances in instrumentation and improved observational techniques have led to the discovery of an increasing number of X-ray sources.

By the late 20th century, thousands of these objects had been detected throughout the universe.

High-energy radiation with waves shorter than those of visible light: X-rays possess the capabilities of penetrating most substances (to varying extents), of acting on a photographic film or plate (permitting radiography), and of causing a fluorescent screen to give off light (permitting fluoroscopy).

Formerly called a Roentgen ray, in low doses X-rays are used for making images that help to diagnose disease, and in high doses to treat cancer.