Tonight's Sky
Sun
Sun
Moon
Moon
Mercury
Mercury
Venus
Venus
Mars
Mars
Jupiter
Jupiter
Saturn
Saturn

Tonight's Sky — Change location

OR

Searching...

Tonight's Sky — Select location

Tonight's Sky — Enter coordinates

° '
° '

See microlensing in action

Here’s how astronomers detect free-floating planets.
Free-floating-planet
This artist’s conception illustrates a Jupiter-like planet alone in the dark of space, floating freely without a parent star. Astronomers recently uncovered evidence for 10 such lone worlds, thought to have been “booted,” or ejected, from developing solar systems. Credit: NASA/JPL-Caltech
In the June issue of Astronomy, author Steve Nadis wrote “Do billions of rogue planets drift through space?” His story talks a great deal about a technique astronomers use called gravitational microlensing.

This NASA artist’s animation illustrates the technique used for finding free-floating Jupiter-mass planets in space. Astronomers think gravitational interactions ejected such worlds early on from their developing solar systems.

The movie shows the central region of the Milky Way and zooms in on a star that brightens. This brightening (exaggerated here) happens when an unseen planet happens to cross in front of it. The planet’s gravity causes the starlight to warp, and this warping results in a brightening of the star. In essence, the planet’s gravity plays the role of a magnifying lens.

The next part of the animation shows a zoomed in view of the microlensing. The blue dot represents the planet (enlarged to make it easy to see). The main star is the central bright dot. When the planet is directly in front of the main star, that star’s multiple images stretch into arcs. This result is a temporary brightening of the star.

The duration of the microlensing event will reveal the rough mass of the passing body. Jupiter-mass objects will cause a star to brighten more quickly, over just a day or two. A passing star would cause a more-distant star to brighten over a period of weeks. The movie ends with an artist’s conception of a free-floating Jupiter-mass world.

The gravitational microlensing shown is based on simulation data from M. Freeman (University of Auckland, New Zealand).
0

JOIN THE DISCUSSION

Read and share your comments on this article
Comment on this article
Want to leave a comment?
Only registered members of Astronomy.com are allowed to comment on this article. Registration is FREE and only takes a couple minutes.

Login or Register now.
0 comments
ADVERTISEMENT

FREE EMAIL NEWSLETTER

Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. View our Privacy Policy.

ADVERTISEMENT
ADVERTISEMENT
RCLP_ASY_0301_mediumrectangle

Untangle the mysteries of our solar system and its moons with this free download.

Find us on Facebook