Hipparcos

Looking for gravity directly.

It combines precision space-based data from the European Space Agency's Gaia and Hipparcos missions with Subaru's extreme adaptive optics.

Gaia and Hipparcos have mapped the exact precise positions of millions of background stars.

OASIS looks for subtle stellar wobbles.

tiny gravitational tugs on those background stars.

Its primary goal is to map the stars of the Milky Way with a scale and precision orders of magnitude greater than ever before.

Gaia's predecessor, Hipparcos, cataloged 120,000 stars.

Gaia blows this out of the water with positions, colors, and brightnesses of nearly 1.7 billion stars.

Gaia can see orders of magnitude fainter and further away than previous missions, but its greatest superpower is its precise astrometry.

It's pretty incredible.

For the first time, we have a complete census of the stellar population far beyond the neighborhood of the sun.

Compare it to the HR diagram of Hipparcos, and we now see the main sequence extending down to include extremely faint red dwarfs.

We also see the full sequence of faint white dwarfs, showing the paths they follow as they slowly fade into blackness.

Completely different approach.

Gaia's absolute astronomy combined with proper motion anomalies between Hipparcos and Gaia, plus radial velocities and imaging.

They're not photographing anything.

They're watching the star get tugged.