Deathwatch for a Star

etacarinae_hst_960Eta Carinae may be about to explode. We’re not sure when—it might be next year, it might be one million years from now. The star’s mass of roughly 100 times our Sun’s makes it an excellent candidate for a full blown supernova, and about 150 years ago, Eta Carinae underwent an unusual outburst becoming one of the brightest stars in the southern sky. Eta Carinae is also the only star currently known to be emitting light from a natural laser. This Hubble image brings out details in the unusual nebula that surrounds this rogue star—two distinct lobes, a hot central region, and strange radial streaks. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks remain unexplained.

Eta Carinae is in the constellation Carina. Carina is Latin for the keel of a ship, and it was formerly part of the larger constellation of Argo Navis (the ship Argo) until that constellation was divided into three pieces, the other two being Puppis (the poop deck), and Vela (the sails of the ship).

Image Credit: NASA

A Reflection Nebula

Reflection Nebula in OrionNGC 1999 is a reflection nebula. A reflection nebula doesn’t emit light on its own. Much like fog around a lamp post, a reflection nebula shines because the light from an embedded source illuminates its dust. NGC 1999 lies close to the Orion Nebula in a region of our galaxy about 1,500 light-year away where new stars are being formed. NGC 1999 is lit by a bright, recently formed star, visible just left of center in this Hubble photo. the star’s white color is caused by its high surface temperature (about 10,000 °C, twice that of the Sun).

Image Credit: NASA

A Holiday Wreath in Space

RS PuppisThis Hubble Space Telescope image resembles a holiday wreath full of sparkling lights. The bright star RS Puppis is at the center of the image and is wrapped in a cocoon of reflective dust lit by the star. RS Puppis is huge, ten times more massive than our sun and 200 times larger. It’s one of the most luminous stars in the class of known as Cepheid variables and brightens and dims over a six-week cycle. Its average intrinsic brightness is 15,000 times greater than our Sun’s.

The surrounding nebula flickers in brightness as pulses of light from the Cepheid move outwards. Hubble has taken a series of photos of light flashes rippling across the nebula in a phenomenon known as a “light echo.” Several can be seen in this picture, most easily the ones moving toward seven o’clock. Even though light travels at around 300,000 km/s, the nebula is so large that reflected light can actually be photographed traversing the nebula. Using these reflections, astronomers are able to measure these light echoes and accurately compute the distance to RS Puppis—6,500 light-years (with a margin of error of only one percent).

Image Credit: NASA

You’re On One of the Pixels in this Image

newrings_cassiniWell, you are if you’re over 15 years old. Back in 2006, the Cassini spacecraft orbiting Saturn drifted in giant planet’s shadow and looked back toward the eclipsed Sun. Saturn’s rings lit up so much that new rings were discovered, although they are hard to see in this image. Saturn’s E ring, the ring created by the newly discovered ice-fountains of the moon Enceladus and the outermost ring visible above, does show up in vivid detail. Far in the distance, at about 10 o’clock on the left, just above the bright main rings, is the almost ignorable pale blue dot of Earth. You may have to click on the image to embiggen it in order to see the Earth.

Image Credit: NASA

Listening to Ganymede

This animation provides auditory and visual presentations of data collected by the Juno spacecraft’s Waves instrument during a flyby of the Jovian moon Ganymede. The animation is shorter than the duration of the flyby because the Waves data is edited onboard to reduce telemetry requirements.

The abrupt change to higher frequencies around the midpoint of the recording occurs as the spacecraft moves from one region of Ganymede’s magnetosphere to another. The actual frequency range of the data is from 10 to 50 kHz. The animation audio has been shifted to a lower range audible to human ears.

Video Credit: NASA

Eyes on Asteroids

NASA has a new 3D real-time visualization tool you can use toexplore the asteroids and comets that approach Earth’s orbit. Eyes on Asteroids also tracks several spacecraft on asteroid related missions and brings this data to any smartphone, tablet, or computer with an internet connection.

The web-based app plots the orbits of every known Near Earth Object and shows detailed information on thems. Using the slider at the bottom of the screen, you can travel quickly forward and backward through time to see their orbital tracks. The database receives twice-daily updates with the latest data, so as soon as a new object is discovered and its orbit is calculated, it’s added to the app.

Image Credit: NASA

Dione

The Cassini spacecraft snapped this picture of the moon Dione orbiting Saturn. At 1122 km in diameter, Dione is the 15th largest moon in the Solar System. Its interior is probably a combination of equal masses of silicate rock and water ice.

Shape and gravity observations collected by Cassini suggest the moon has a  core of around 400 km of rock surrounded by a roughly 160 km envelope of water, probably in the form of ice. However, some models suggest the lowermost part of this layer could be in the form of an internal liquid salt water ocean.

Image Cedit: NASA