A fruit fly starts buzzing around food at a picnic, so you wave your hand over the insect and shoo it away. But when the insect flees the scene, is it doing so because it is actually afraid? Using fruit flies to study the basic components of emotion, a new Caltech study reports that a fly's response to a shadowy overhead stimulus might be analogous to a negative emotional state such as fear—a finding that could one day help us understand the neural circuitry involved in human emotion. 

Light can come in many frequencies, only a small fraction of which can be seen by humans. Between the invisible low-frequency radio waves used by cell phones and the high frequencies associated with infrared light lies a fairly wide swath of the electromagnetic spectrum occupied by what are called terahertz, or sometimes submillimeter, waves. Exploitation of these waves could lead to many new applications in fields ranging from medical imaging to astronomy, but terahertz waves have proven tricky to produce and study in the laboratory. Now, Caltech chemists have created a device that generates and detects terahertz waves over a wide spectral range with extreme precision, allowing it to be used as an unparalleled tool for measuring terahertz waves.

Caltech and UC Santa Cruz researchers say Earth belongs to a second generation of planets.

Facing a challenge akin to solving a 1,000-piece jigsaw puzzle while blindfolded—and without touching the pieces—many structural biochemists thought it would be impossible to determine the atomic structure of a massive cellular machine called the nuclear pore complex (NPC), which is vital for cell survival.

The central regions of many glittering galaxies, our own Milky Way included, harbor cores of impenetrable darkness—black holes with masses equivalent to millions, or even billions, of suns. What is more, these supermassive black holes and their host galaxies appear to develop together, or "co-evolve." Theory predicts that as galaxies collide and merge, growing ever more massive, so too do their dark hearts.

For the first time, a mission designed to set its eyes on black holes and other objects far from our solar system has turned its gaze back closer to home, capturing images of our sun. NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, has taken its first picture of the sun, producing the most sensitive solar portrait ever taken in high-energy X-rays.

Observations by NASA's Curiosity Rover indicate Mars' Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years.