Tropical Storm Irma seen by Suomi NPP satellite

On August 30 at 11:36 a.m. EDT (1536 UTC) NASA-NOAA's Suomi NPP satellite captured a visible image of Tropical Storm Irma in the Eastern Atlantic Ocean.

Image Credit: NASA/NOAA, Goddard Rapid Response Team

Galaxy Cluster ACT-CL J0102-4915

When astronomical objects are named, astronomers like to pick out notable features for inspiration — for example, the Whirlpool Galaxy with its pinwheeling arms, or the Needle Galaxy, which appears as a long, thin streak of silver across the sky.

This image shows a galaxy cluster known as El Gordo, or “the fat one”, a very distant object that lies some ten billion light-years away from us. This grouping of galaxies certainly lives up to its nickname; it is the largest known galaxy cluster in the distant Universe and contains several hundred galaxies. What’s more, new NASA/ESA Hubble Space Telescope observations show that it is actually some 43 percent heavier than previously thought, with a mass some three million billion times the mass of the Sun — which is 3000 times the mass of our own galaxy, the Milky Way.

A small fraction of the cluster’s immense mass is locked up in the galaxies that inhabit it, and a larger fraction is held in hot gas that fills its entire volume, but the majority is made up of the infamous, and invisible, dark matter. The location of this dark matter is mapped out in the blue overlay. Although galaxy clusters as massive as this do exist in the nearby Universe, for example the Bullet Cluster, nothing like this has ever been seen to exist so far back in time, when the Universe was roughly half of its current age of 13.8 billion years.

Astronomers previously weighed El Gordo back in January 2012, studying the unusual cluster’s appearance and dynamics in the X-ray part of the spectrum. This new Hubble study instead analysed how the huge cluster affected the space around it to get an idea of its mass. Large clumps of mass warp space and distort the view of more distant objects. This process, known as gravitational lensing, allows astronomers to estimate the mass of the clumps that are causing this distortion.

Image Credit: NASA, ESA, J. Jee (University of California, Riverside, USA)
Explanation from: https://www.spacetelescope.org/images/potw1414a/

New stars in Canis Major

Dozens of newborn stars sprouting jets from their dusty cocoons have been spotted in images from NASA's Spitzer Space Telescope. In this view showing a portion of sky near Canis Major, infrared data from Spitzer are green and blue, while longer-wavelength infrared light from NASA's Wide-field Infrared Survey Explorer (WISE) are red.

The jets appear in green, while young stars are a yellow-orange hue. Some of the jets can be seen as streaks, while others appear as blobs because only portions of the jet can be seen. In some cases, the stars producing jets can't be seen while their jets can. Those stars are so embedded in their dusty cocoon that they are too faint to be seen at Spitzer's wavelengths.

This is a lesser-known region of star formation, located near the outer edge of our Milky Way galaxy. Spitzer is showing that even these more sparse regions of the galaxy are aglow with stellar youth.

The pink hues are from organic star-forming molecules called polycyclic aromatic hydrocarbons. Stars in the pink regions are a bit older than the rambunctious ones spewing jets, but still relatively young in cosmic terms.

In this image, Spitzer's 3.6- and 4.5-micron data are blue and green, respectively, while WISE's 12-micron data are red. The Spitzer data were taken as part of the mission's Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 360, or Glimpse 360 project, which is pointing the Spitzer Space telescope away from the galactic center to complete a full 360-degree scan of the Milky Way plane.

Image Credit: NASA/JPL-Caltech/University of Wisconsin
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA17018