A One-in-a-Million Shot: Microlensing Alignment Events Quiz

If the stars are moving past each other at high speeds and the alignment must be perfect, then once they pass, they will likely never align for us again; therefore, these are strictly one-time events.

If a lone planet passes between Earth and a distant star, its mass will still bend the light; if we see a small lensing event without a larger star event nearby, then we have found a rogue planet.

If the method relies on a background star as a light source, and if those stars are far away, then we can detect planets orbiting lens stars that are thousands of light-years from Earth.

If the stars are moving independently and we cannot control their paths, the alignment is a random coincidence that happens once and cannot be re-observed or easily predicted.

If a planet is much smaller and has less gravity than a star, its lensing effect covers a much smaller area; if the area is small, the alignment lasts for a much shorter duration of time.

If microlensing depends on the planet's gravity bending light from a different background star, then the planet does not need to pass in front of its own star for us to detect it.

If Einstein’s theory of relativity states that mass curves space, and if gravity is the manifestation of that curvature, then gravity is the force that bends the light path.

If there are more stars, an alignment is more likely; if the lens is more massive, it has a larger gravitational "reach" (Einstein radius), making it easier to catch the light of a background star.

If the light being analyzed originates from a specific object in the background, then that object is the source of the radiation.

If the light from a distant source is being redirected, then the object responsible for that redirection is the "lens"; in this case, it is the star located between Earth and the source.

If a foreground star moves into a position where it is perfectly lined up with a distant star, and if the gravity of the foreground star acts as a lens, then the light from the distant star will be temporarily magnified for the observer.

If the foreground star moves in front of the source, the light goes up and then down symmetrically; if a planet is there, it adds a small spike; once the stars are no longer aligned, the brightness returns to normal.

If the probability of an alignment depends on how many stars are in your field of view, and if the center of the galaxy (Galactic Bulge) has the most stars, then looking there provides the best chance of witnessing an event.

If gravity focuses the light rays that were originally going to miss Earth, then more light reaches our telescopes; if more light arrives, the star appears brighter even if its physical size remains the same.

If a planet is orbiting the foreground (lens) star, and if that planet also has gravity, then it will act as a secondary lens; if it passes the line of sight, it will create a brief, additional surge in brightness.

If we do not know the exact position and velocity of every dim star or planet in the galaxy, and if the alignment must be perfect, then we cannot predict these events in advance and must instead monitor millions of stars at once to catch them.

If the phenomenon relies on light being bent as it travels toward us, then there must be a starting light (Source), a middle object to bend it (Lens), and someone to receive the light (Observer).

If space is mostly empty and stars are tiny compared to the distances between them, and if an alignment must be nearly perfect to cause lensing, then the statistical probability for any specific star is roughly one in a million.

If the alignment is not permanent and depends on the random motion of two unrelated stars, then the meeting of their positions in the sky is described as a chance encounter.

If stars are separated by trillions of miles of empty space, then the likelihood of any two stars lining up perfectly from our perspective is extremely low; therefore, these alignments are considered very rare.