NASA’s Swift satellite recently detected a growing flow of high-energy X-rays from somewhere near the center of our galaxy. The outburst, pictured in this illustration, was produced by a rare X-ray nova and announced the presence of a previously unknown stellar-mass black hole. (Image: NASA)

A school of Kokanee Salmon returns to the streams from which they were hatched. There, they select a mate, spawn and die. As the salmon make their annual fall migration, both sexes turn from their usual silver/blue color to a brilliant red. (Photo: United States Forest Service)

This image from the right Mast Camera (Mastcam) of NASA’s Mars rover Curiosity shows sand and dust lifted by the rover’s first use of the scoop on its robotic arm. (Photo: NASA)

A 700kg crocodile called Rex calmly waits just beneath the water’s surface for some food after coming out of a three-month hibernation at the Wild Life Sydney Zoo in Sydney, Australia. (Photo: AP)

No, these aren’t miniature UFOs. The tiny cube-shaped satellites were released into space from the International Space Station’s Kibo laboratory. One of these little CubeSats was developed by student interns at San Jose State University and will be used for a communications experiment (Photo: NASA)

The interior of the neutrino detector at Daya Bay in the People’s Republic of China, where a multi-national team of researchers from China, the United States, Taiwan, and the Czech Republic are studying neutrino oscillations. Neutrinos are electrically neutral elementary subatomic particles that can travel through great distances of matter without being affected by it. (Photo: Lawrence Berkeley National Laboratory)

This combined image from NASA is of the Helix Nebula, which has also been called the “Eye of God.” At the nebula’s heart is a dying star. In its death throes, the star’s outer layers unravel into space and are set aglow by powerful ultraviolet radiation pumped out by its hot stellar core. (Photo: NASA)

A monarch butterfly stops for a rest during its fall migration. The butterfly can journey up to nearly 5,000 km to its winter home in Mexico or Southern California. In the spring, they make another epic trip as they return to areas up north. (Photo: USDA)

This time-exposure photo shows the Falcon 9 SpaceX rocket lifting off from the Cape Canaveral Air Force Station in Cape Canaveral, Florida. The rocket, with its Dragon space capsule payload, just made its first commercial delivery of supplies to the International Space Station. (Photo: AP)

NASA’s Solar Dynamics Observatory (SDO) recently caught this spectacular coronal mass ejection (CME). The sun spat out a more than 804,672-km-long filament of solar material that had been hovering in the sun’s corona. The CME did not travel directly toward Earth, but did connect with Earth’s magnetic environment, or magnetosphere, with a glancing blow that left beautiful auroras in its wake. (Photo: NASA)

The world’s smallest scale, which cannot be seen with the human eye. Developed by a team led by scientists at the California Institute of Technology (Caltech), the device measures the mass of individual molecules.  It is so tiny that an electron miscroscope is needed to photograph it.  The scale bar at the bottom is two microns (millionths of a meter).  (Photo: Caltech / Scott Kelber and Michael Roukes)

Russian cosmonaut Gennady Padalka, Expedition 32 commander, participates in a session of extravehicular activity (EVA) to continue outfitting the International Space Station. (Photo: NASA)

A Concentrating Solar Power (CSP) system in Albuquerque, New Mexico. CSPs concentrate a large area sunlight with mirrors and lenses.  The concentrated sunlight is then converted into heat, which drives a turbine power system to produce electricity. (Photo: Randy Montoya/Sandia National Laboratory)

The famous “boot” shape of Italy is illuminated by the country’s night lights.  In this photo, taken from aboard the International Space Station, you can also see Sardinia and Corsica just above the left center of the photo. Sicily is at lower left.  (Photo: NASA)

Beluga whales at Marine Land in Canada pose for the camera. Marine mammals, such as these whales, are protected within the United States by the Marine Mammal Protection Act (MMPA) of 1972. Before they can be brought into the US or put on public display, permits, issued by the NOAA (National Oceanic and Atmospheric Administration), must be obtained. (Photo: Jennifer Skidmore/NOAA)

A composite image taken by NASA’s Chandra X-ray Observatory shows a superbubble in the Large Magellanic Cloud (LMC), The massive stars produce intense radiation, expel matter at high speeds, and race through their evolution to explode as supernovas. The winds and supernova shock waves carve out huge cavities called superbubbles in the surrounding gas. (Photo: NASA)

Droughts have taken a toll on many parts of the United States. As a result, a number of wildfires, mostly in the western US, have broken out. According to NOAA, by Aug. 8, 2012, wildfires had consumed more than 4 million acres of land. Here, firefighters continue burnout operations on the Sawmill Canyon Fire in Wyoming. (Photo: U.S. Forest Service)

The first of four towers about to be lifted as work continues on a giant wind turbine being installed at the National Renewable Energy Laboratory’s (NREL) in Colorado.  (Photo: Dennis Schroeder/National Renewable Energy Laboratory)

Of course, our Science Images of the Week would not be complete without a snapshot from Mars. Here, the Curiosity rover takes a picture of tracks it made while cruising the surface of Mars. (Photo: NASA)

This artist’s concept shows the sky crane maneuver during the descent of NASA’s Curiosity rover to the Martian surface. (Image: NASA/JPL-Caltech)

A close-up view of a South American scarab dung beetle (Oxysternon conspicillatum) (Photo: J. Mark Rowland/Douglas J. Emlen/Courtesy: National Science Foundation)

From the Hubble Space Telescope – Star Cluster R136 bursts out (Photo: NASA, ESA, & F. Paresce (INAF-IASF), R. O’Connell (U. Virginia), & the HST WFC3 Science Oversight Committee)

Engineers checking out the Inflatable Reentry Vehicle Experiment (IRVE-3) at NASA’s Langley Research Center in Hampton, Virginia (Photo: NASA Langley/Sean Smith)

A fluorescent micrograph capturing the presence of bacteria (shown in green) on the surface of an emerging lateral root of the Arabidopsis, a small flowering plant related to cabbage and mustard (Photo: Sarah Lebeis/University of North Carolina)

As seen through a window in the Cupola, the International Space Station’s Canadarm2 grapples the unpiloted Japan Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle (HTV-3). (Photo: NASA)

From NASA’s Chandra X-ray Observatory – X-rays From a young supernova remnant (Image: X-ray: NASA/CXC/STScI/K.Long et al., Optical: NASA/STScI)

A new amphibian species, the ‘Mr. Burns Beaked Toad’ (Credit: USFWS)

An aurora borealis visible in the northern sky over Merritt Reservoir in Valentine, Nebraska (Photo: Howard Edin/Courtesy: National Science Foundation)