Joe PalcaJoe Palca is a science correspondent for NPR.
When Mars is "in opposition," it, Earth and the sun are all in alignment. (Note: This is a diagram meant to illustrate the concept of opposition. It is not drawn to scale.)
An early prototype of the silicon-chip-sized particle accelerator that physicists at Stanford are working on. Eventually, miniature accelerators might have a role in radiating tumors, the scientists say.
SLAC National Accelerator Laboratory
This artist's impression shows the dust torus around a super-massive black hole. Black holes lurk at the centers of active galaxies. The jets emanating from the black hole send neutrinos hurtling into space.
ESA/NASA/the AVO project/Paolo Padovani
Global map of Mars showing a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter spacecraft.
This red blood cell is swollen by the malaria parasite. In this image from a transmission electron micrograph, the blood cell has been colored red and the single-cell malaria parasite has been colored green.
Dr. Tony Brain/Science Source
This is an artist's concept of a plume of water vapor thought to be ejected off of the frigid, icy surface of the Jovian moon Europa, located 500 million miles from the sun.
NASA, ESA, and K. Retherford
An artist's rendition of NASA's InSight lander, which is expected to launch on Saturday morning. InSight will monitor the Red Planet's seismic activity and internal temperature.
An image from an electron microscope shows a type II alveolar cell, found in the air sacs of lungs. In the cell's cytoplasm (pink) are lamellar bodies (purple), which contain surfactant.