spaceSpace and Physics

Colorful Map Reveals Microwaves In The Milky Way Produced By "Spinning Dust"


Jonathan O'Callaghan

Senior Staff Writer

1155 Colorful Map Reveals Microwaves In The Milky Way Produced By "Spinning Dust"
The Planck satellite created this map of the Milky Way's microwaves. M. Peel / JCBA / Planck / ESA.

What happens when you produce a map of microwaves in the Milky Way? Well, it ends up looking something like the image above.

Created using the European Space Agency’s (ESA) Planck satellite, the image reveals microwaves coming from all corners of the galaxy. The color represents their angle, and the brightness is their intensity. Planck, launched in 2009, has previously been used to study ancient light from the Big Bang, but this time turned its attention to microwaves.


Microwaves in the Milky Way are created in a number of processes including particle collisions in the interstellar plasma, the vibration of dust caused by heat and “spinning” dust grains, which is called anomalous microwave emission (AME). The spinning dust is the result of electrical charges, and was first observed as a by-product of Cosmic Microwave Background (CMB) observations, the remnant radiation left over from the Big Bang.

Each process produces a different strength of microwave, which can be separated by telescopes. This particular image uses AME.

It was presented by Dr. Mike Peel and Dr. Paddy Leahy of the Jodrell Bank Centre for Astrophysics (JCBA) at the National Astronomy Meeting (NAM 2015) in Llandudno, Wales, last week. The shape of the image is a result of how Planck maps the sky, observing “strips” of the Milky Way and combining them together to create a single snapshot.

A second image, seen right, reveals a large amount of microwave emissions around the Lambda Orionis nebula, located at the “head” of the Orion constellation. This ring is 200 light-years across and is a result of the AME process.


Aside from the change in microwave intensity from different corners of the galaxy, a large “yellow” feature can also be seen covering a third of the sky in the initial image, highlighted by the dotted ellipse. Dubbed Loop 1, it was found 50 years ago but scientists are still unsure how far away it is – anywhere from 400 to 25,000 light-years. This means that its size can also not be determined yet.

According to, many scientists think Loop 1 is a "pre-existing cavity in the interstellar gas and dust that was re-energized by supernovas and began emitting microwaves."

Central image: Courtesy of M. Peel / JCBA / Planck / ESA.


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