Observation
When a planetary-sized object passes in front of a background star, its gravitational field causes a momentary increase in the visible brightness of the background star. This is known as microlensing. Astrophysicist Takahiro Sumi of Osaka University in Japan and colleagues, who form the Microlensing Observations in Astrophysics (MOA) and the Optical Gravitational Lensing Experiment (OGLE) collaborations, carried out a study of microlensing which they published in 2011. They observed 50 million stars in our galaxy using the 1.8 meter MOA-II telescope at New Zealand's Mount John Observatory and the 1.3 meter Warsaw University Telescope at Chile's Las Campanas Observatory. They found 474 incidents of microlensing, just 10 of which were brief enough to be planets of around Jupiter's size with no associated star in the immediate vicinity. The researchers estimated from their observations that there are nearly two free-floaters for every star in our galaxy. Other estimations suggest a much larger number, up to 100,000 times more free-floating planets than stars in our Milky Way.
Read more about this topic: Rogue Planet
Famous quotes containing the word observation:
“Let observation with extensive view;
Survey mankind, from China to Peru;”
—Samuel Johnson (1709–1784)
“I should say that the most prominent scientific men of our country, and perhaps of this age, are either serving the arts and not pure science, or are performing faithful but quite subordinate labors in particular departments. They make no steady and systematic approaches to the central fact.... There is wanting constant and accurate observation with enough of theory to direct and discipline it. But, above all, there is wanting genius.”
—Henry David Thoreau (1817–1862)