Gravity’s Lens: Gravitational Microlensing Explained Quiz

If gravity from a foreground object curves the space around it, and if light from a distant background star travels through that curved space, then the light is focused and magnified toward the observer, behaving like a glass lens.

If Einstein's General Relativity is correct, then gravity curves spacetime itself; if light follows the "straightest" path through this curved space, then it bends regardless of the fact that photons have no rest mass.

If the microlensing process requires light to be "lensed," and if that light must originate from an object far behind the lensing mass, then the origin of the light is defined as the source star.

If a distant source star, a foreground lensing object, and the observer are aligned in a perfectly straight line, then the distorted light from the source will be stretched into a symmetrical circle around the lens.

If stars are constantly moving in the galaxy, then the alignment needed for lensing is a rare, transient coincidence; if a planet is present, it adds its own gravity to the lens regardless of its distance from its host.

If the main star acts as a lens to create a large magnification curve, and if a planet orbiting that star also acts as a tiny lens, then the planet will create its own brief, additional "spike" of brightness on top of the star's curve.

If a planet exists alone in space, it still has mass; if that mass passes in front of a distant star, it will create a tiny lensing event; therefore, microlensing is the only method that can find planets without host stars.

If the mathematical description of light bending involves a specific distance from the lens where the light is focused, then that characteristic distance is named the Einstein radius.

If stars in the Milky Way are moving in different directions and speeds, and if microlensing requires two stars thousands of light-years apart to align perfectly from Earth's view, then the timing is random and cannot be easily scheduled.

If microlensing is a geometric alignment of light, then it must involve a light provider (source), a light bender (lens), and a light recorder (the observer).

If a more massive object has a larger gravitational field (Einstein radius), and if a larger field takes more time for the background star to pass through, then higher mass results in a longer-lasting lensing event.

If the Einstein radius of a typical lens star often corresponds to the region where water freezes (the snow line), and if lensing is most effective at that radius, then this method is uniquely suited to find planets in that specific orbital zone.

If the geometry of a multi-mass lens creates specific lines or points in space where light is intensely focused, then these high-magnification boundaries are known as caustics.

If microlensing requires a high density of background stars to increase the chance of an alignment, and if the center of our galaxy contains the highest concentration of stars, then the Galactic Bulge is the best place to monitor.

If the method relies on gravity rather than the planet's own light, then it can find small, distant, or dark objects that other methods (like transits or direct imaging) would miss.

If any object with mass (star, planet, or galaxy) curves space, then any mass can create an Einstein ring; therefore, it is a property of gravity itself, not specifically the type of object.

If the gravitational lens acts like a magnifying glass to make a distant star appear brighter than its actual state, then the ratio of the new brightness to the original brightness is the magnification.

If NASA is launching a wide-field infrared telescope specifically designed to monitor millions of stars in the galactic center for lensing spikes, then that mission is the Nancy Grace Roman Space Telescope (formerly WFIRST).

If transits require a planet to pass "in front" of its star to block light, but microlensing uses the planet's gravity to "bend" light from a different star, then the physical mechanisms and limitations are entirely different.

If the detection is based on the brightening of the background source star, and if the lens object (like a black hole or a brown dwarf) is completely dark, then we can still detect the lens by observing its gravitational effect on the source light.