NASA expects more than 1,000 wide-orbit planets from stars that briefly brighten

Each of these detections comes from an event that happens once. The two stars involved may lie thousands of light-years apart and only appear to line up from here ^[19], and astronomers cannot choose a foreground star and wait for it to lens something behind it ^[8]. Once the alignment breaks and the background star fades back down ^[5], that same configuration will generally never occur again ^[8].

Roman will observe its main survey fields roughly once every 12 minutes ^[9], which works out to about 120 looks at each field per day of continuous observing ^[16], across six intensive seasons ^[9]. The survey is built on frequency: watch that many stars that often, and large numbers of the rare alignments should fall inside the field of view ^[10].

Crowding is why the survey needs a space telescope. Roman pairs sharp infrared imaging with an unusually wide field of view, and that combination lets it image huge numbers of stars repeatedly even in the extremely crowded regions toward the center of the galaxy ^[13].

One data stream yields both planet counts: the bulge survey is designed primarily to catch microlensing events, and the repeated brightness measurements it collects along the way feed the transit search too ^[20].

Most exoplanets known today orbit close to their stars, and Roman will probe the colder, more distant regions of planetary systems that remain much less explored ^[12]. That distance is what makes the resulting catalog useful. The author of the Conversation piece, an exoplanet scientist, frames the technique as a complement: no single observing method can reveal every type of planet, and microlensing helps find planets that are hard to find other ways ^[14]. The article itself does not compare microlensing with radial-velocity surveys or quantify what existing catalogs miss ^[18], so the supported claim stays narrow: the cold sample is sparse today, and Roman will add to it.

The planets themselves stay unseen: microlensing works even when a planet is far too faint and distant to image directly ^[7], because the measurement is made on the light of a star behind it ^[3].