XMM-Newton & Chandra revise distance to the outer spiral arms

This artist’s impression depicts the structure of our galaxy, the Milky Way, based on data from ESA's Gaia and illustrates how scientists have revised the position of its outer arms thanks to observations from ESA's XMM-Newton and NASA's Chandra.

The two X-ray telescopes have spotted the aftermath of three bright cosmic explosions echoing through the outer spiral arms of our galaxy. By measuring the distance to these echoes, a research team found that the outer arms are up to 10% further away than we thought.

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[Image description: An artist’s impression of what our home galaxy, the Milky Way, might look like face-on, as viewed from above the disc of the galaxy, with its spiral arms and bulge in full view. In the centre of the galaxy, the bulge shines as a hazy oval, emitting a faint golden gleam. Starting at the central bulge, several glistening spiral arms coil outwards, creating a circle-shaped spiral. The position of the Sun is indicated as a small yellow dot within the spiral. Two sets of two lines roughly trace the extremities of the outer arms labelled ‘Outer Arm’ and ‘Outer Scutum-Centaurus Arm’, drawing four arcs. In each set, a magenta line traces the newly determined position of the outer arm by XMM-Newton and Chandra; on the inside of the magenta arc, a white dashed arc traces the position of that arm derived from older estimates.]