SpaceTime

Twenty-one light years away, in the constellation Cassiopeia, a planet by the name of HD219134 b orbits its star with a year that is just three days long. With a mass almost five times that of Earth, it is what is known as a super-Earth. Unlike our planet, however, these super-Earths were formed at high temperatures close to their host star and contain high quantities of calcium, aluminum and their oxides – including sapphire and ruby. HD219134 b is one of three candidates likely to belong to a new, exotic class of exoplanets. These objects are completely different from the majority of Earth-like planets. They have 10 to 20 percent lower densities than Earth. Researchers looked at different scenarios to explain the observed densities. For example, a thick atmosphere could lead to a lower overall density. But two of the exoplanets studied, 55 Cancri e and WASP-47 e, orbit their star so closely that their surface temperature is almost 3,000 degrees and they would have lost this ...

At its closet on December 16, the comet 46P/Wirtanen — one of the brightest in years — was approximately 11.4 million kilometers from Earth, or 30 times the distance from the Earth to the moon. The ALMA image of comet 46P/Wirtanen zooms-in to very near its nucleus – the solid “dirty snowball” of the comet itself — to image the natural millimeter-wavelength “glow” emitted by molecules of hydrogen cyanide (HCN), a simple organic molecule that forms an ethereal atmosphere around the comet. ALMA, using its remarkable ability to see fine details, was able to detect and image the fine-scale distribution of this particular molecule. The HCN image shows a compact region of gas and an extended, diffuse, and somewhat asymmetrical, pattern in the inner portion of the coma. Due to the extreme proximity of this comet, most of the extended coma is resolved out, so these observations are only sensitive to the innermost regions, in the immediate vicinity of the nucleus. This and previous obse...

This image is a composite of observations made of Saturn in early 2018 in the optical and of the auroras on Saturn’s north pole region, made in 2017. In contrast to the auroras on Earth the auroras on Saturn are only visible in the ultraviolet — a part of the electromagnetic spectrum blocked by Earth’s atmosphere — and therefore astronomers have to rely on space telescopes like the NASA/ESA Hubble Space Telescope to study them.  Credit:  ESA/Hubble, NASA, A. Simon (GSFC) and the OPAL Team, J. DePasquale (STScI), L. Lamy (Observatoire de Paris) In 2017, over a period of seven months, the NASA/ESA Hubble Space Telescope took images of auroras above Saturn’s north pole region using the Space Telescope Imaging Spectrograph. The observations were taken before and after the Saturnian northern summer solstice. These conditions provided the best achievable viewing of the northern auroral region for Hubble. On Earth, auroras are mainly created by particles or...

This spectacular image of the Carina nebula reveals the dynamic cloud of interstellar matter and thinly spread gas and dust as never before.  Credit:  ESO/J. Emerson/M. Irwin/J. Lewis About 7500 light-years away, in the constellation of  Carina , lies a nebula within which stars form and perish side-by-side. Shaped by these dramatic  events, the  Carina Nebula  is a dynamic, evolving cloud of thinly sprea d interstellar gas and dust. Spanning over 300 light-years, the Carina Nebula is one of the Milky Way's largest star-forming regions and is easily visible to the unaided eye under dark skies. Unfortunately for those of us living in the north, it lies 60 degrees below the celestial equator, so is visible only from the Southern Hemisphere. The massive stars in the interior of this cosmic bubble emit intense radiation that causes the surrounding gas to glow. By contrast, other regions of the nebula contain dark pillars of dust cloak...