The Milky Way in 3D

A new 3D map of the Milky Way reveals the structure of our galaxy as never before, according to a study published this week in the journal Science.

Why it matters: By modeling the Milky Way, scientists can piece together the galaxy’s history, explaining why it looks the way it does and placing it in context with other galaxies observed around our own.

What they found: The new study confirms the Milky Way’s disk appears to be warped in an extreme way.

• “We don't know for sure, but we think that the warp may have been caused by interactions with satellite galaxies…” Dorota Skowron, one of the study’s authors tells Axios via email. “Other possibilities point to interactions with intergalactic gas or dark matter.”
• The team measured the distances from the Sun to more than 2,400 pulsing stars called Cepheids in order to map the galaxy from the inside out.
• They found the Milky Way does have four arms arranged in a spiral structure, as earlier studies have suggested.

What’s next: Mapping variable stars like Cepheids on the other side of the Milky Way’s center could inform future research about the shape of our galaxy, astrophysicist Richard de Grijs, who didn’t take part in the new study, tells Axios via email.

• If the other side of the disk is also warped “this 3D feature is most likely caused by dynamics and kinematics of the stars in the disk,” de Grijs, who recently co-authored another study mapping the galaxy with Cepheids, said.
• “If this is only seen on one side, it may be due to the gravitational effects of or merger with a smaller ‘dwarf’ galaxy in the past.”
• The bottom line: It isn't a complete map of the Milky Way, but it sets a foundation for understanding how our galaxy and others around it evolved.