Spinning Mystery: Galaxy Rotation Curves Quiz

The primary anomaly is that stars maintain constant speed at the edges. According to classical physics, orbital speeds should decrease as distance from the center increases. This observation indicates that the gravitational pull remains strong far beyond the visible boundaries of the galaxy, suggesting the presence of significant hidden mass.

It is false because visible matter is not sufficient to explain the observed rotation speeds. Calculations based on the light from stars and gas show there is not enough ordinary matter to generate the necessary gravity. This deficit implies that an invisible component must provide the extra force required to hold the galaxy together.

The horizontal axis represents the distance from the center of the galaxy. By plotting this against orbital velocity, scientists can visualize how the speed of celestial objects changes as they move outward. This graphical representation is essential for identifying where galactic mass distribution deviates from what is visible to the eye.

The correct term is dark matter halo. The flat shape of rotation curves indicates that mass is distributed in a large, spherical region extending far beyond the visible disk. This invisible halo provides the gravitational influence needed to keep stars at the galactic periphery moving at high orbital velocities.

The characteristics are that it does not emit light and interacts via gravity. Because dark matter is non-luminous, it cannot be seen through telescopes that detect electromagnetic radiation. However, its gravitational effect is clearly visible through the way it influences the orbital speeds of stars in the outer regions of galaxies.

The velocity would decrease inversely with distance. In a system where mass is centralized, such as our solar system, objects further away move more slowly. The fact that galaxy rotation curves do not show this decrease is the key evidence that mass is actually spread out far into the distance.

This is true because the observed speeds require much more mass than what we can see. Since the stars and gas we observe cannot account for the gravity needed to maintain these speeds, it is concluded that the majority of matter must be non-luminous, effectively forming the invisible dark matter.

The force responsible is gravity. Gravity acts as the invisible tether that pulls stars toward the center of the galaxy, balancing their outward momentum. Studying rotation curves allows scientists to calculate exactly how much gravitational pull is present and compare it to the amount of visible matter available.

Objects travel faster than predicted. Based on the visible light emitted by stars and gas, the orbital velocity should drop off at the galactic edge. Instead, observations show these objects moving at high speeds, which is a major anomaly that led to the discovery of missing gravitational mass.

The astronomer is Vera Rubin. Her meticulous observations of spiral galaxies showed that the outer stars were moving just as fast as the inner stars. This groundbreaking work provided the robust observational evidence needed to confirm that galaxies contain a vast amount of unseen matter, revolutionizing our understanding of space.

The factors are total mass distribution and distance from the core. The rotation curve is a direct map of how mass is spread throughout the system. By measuring velocity at various distances from the core, astronomers can determine how much matter is present, including both the visible stars and the invisible halo.

They would fly off into space. Without the extra gravitational pull provided by dark matter, the visible matter would not have enough strength to hold onto stars moving at such high speeds. Dark matter acts as a necessary "glue" that keeps the fast-moving outer regions of galaxies intact.

This is true because the orbital velocity does not decline as expected. When a graph shows a horizontal line at large distances, it is called a "flat" curve. This universal feature of spiral galaxies proves that there is a significant amount of mass located far beyond where the light from stars fades out.

The correct term is mass-to-light ratio. This ratio compares the total mass calculated from orbital velocities to the mass calculated from visible light. A high ratio indicates that there is much more matter present than can be accounted for by the stars, pointing directly toward the presence of dark matter.

The dark matter halo is responsible for the flat curve. While stars and the central black hole provide gravity in the inner regions, their influence weakens at greater distances. The continued high speeds of outer stars require a massive halo of dark matter to provide consistent gravitational pull.

This is true because mass anomalies are not limited to spiral galaxies. Observations of the velocity dispersion in elliptical galaxies and the movement of galaxies within clusters all indicate that there is significantly more gravity than visible matter can provide. This suggests that dark matter is a universal component of all galactic structures.

They use the Doppler shift of spectral lines. When objects move toward or away from an observer, the frequency of their light shifts. By measuring this shift in the spectra of stars and hydrogen gas, astronomers can calculate precise orbital velocities and construct accurate rotation curves for distant galaxies.

The prediction is that speed decreases with distance. According to Kepler’s laws, the further an object is from the center of mass, the slower it should orbit. Because galaxies do not follow this pattern, it provides clear evidence that mass is not concentrated only at the center but is distributed throughout.

The rotation curve shape and the mass-to-light ratio would change. If gravity worked differently at low accelerations, we might explain the orbital speeds without needing invisible mass. This would change how we interpret the curves and our calculations of how much matter is actually present in the universe.

The correct answer is atomic hydrogen. Hydrogen gas extends much further into space than starlight does. By detecting the 21cm radio emissions from this gas, astronomers can measure rotation speeds in the outermost reaches of a galaxy, providing the most complete picture of mass distribution and dark matter.