Category Astronomy/Space

You can tell Earth and the moon’s shadows apart by their edges: Earth’s is fuzzy, while the moon’s is sharp and distinct. This is because Earth’s atmosphere absorbs some of the sun’s light, creating an ill-defined edge. On the other hand, the moon has no atmosphere, producing a crisp horizon. Credit: NASA/SDO

Early in the morning of Sept. 1, 2016, NASA’s Solar Dynamics Observatory, or SDO, caught both Earth and the moon crossing in front of the sun. SDO keeps a constant eye on the sun, but during SDO’s semiannual eclipse seasons, Earth briefly blocks SDO’s line of sight each day – a consequence of SDO’s geosynchronous orbit. On Sept. 1, Earth completely eclipsed the sun from SDO’s perspective just as the moon began its journey across the face of the sun...

Images of Ceres made using combined Dawn and 2005 HST ultraviolet-visible wavelength images. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Philip Stooke/Ian Regan

Hubble observations of the dwarf planet Ceres have discovered the first evidence of sulfur, sulfur dioxide and graphitized carbon found on an asteroid. The sulfur species are likely associated with regions of recent activity, reports Planetary Science Institute Senior Scientist Amanda Hendrix. The discoveries were made by comparing Ceres’ UV-visible spectra to laboratory measurements. The new HST observations are complementary to observations being made by instrument on the Dawn spacecraft in orbit at Ceres, covering additional wavelengths.

The presence of graphitized carbon is consistent with weathering of carbonaceous material on t...

IBIS/ISGRI ScW image sequence (22–60 keV) from number 25 to 27 (revolution 1614) of the newly discovered transient source IGR J20344+3913 (encircled). Credit: Sguera et al., 2016.

Astronomers have identified two new X-ray sources in the galactic plane with short outbursts and very fast rise times, a category known as fast X-ray transients (FXTs). The newly detected FXTs were found in the archival data of ESA’s INTErnational Gamma-Ray Astrophysics Laboratory (NTEGRAL) spacecraft. FXTs are very difficult to detect because they occur at unpredictable locations and times and their activity is very brief. INTEGRAL is one of the space observatories capable of detecting such elusive X-ray sources...