Astronomy
What would happen if a kilometer-diameter asteroid hit Earth, and how are scientists working to prevent such catastrophic impacts?
A kilometer-diameter asteroid impact would likely end human civilization by causing truly global devastation and potential extinction events. These massive objects pose an existential threat due to their ability to create worldwide catastrophic effects that could wipe out entire species. To address this threat, NASA and the global astronomical community have established planetary defense programs focused on discovering and tracking potentially hazardous objects (PHOs). While significant progress has been made in locating larger asteroids, ongoing international cooperation and preparedness efforts are essential to protect humanity from future asteroid impacts.
Watch clip answer (00:20m)
NASA
00:25 - 00:45
What is the current state of our knowledge regarding potentially hazardous asteroid impacts on Earth?
According to asteroid detection specialists and NASA researchers, we have reached a level of scientific certainty that asteroid impacts will occur in the future - it's not a matter of "if" but "when." The astronomical and planetary defense communities have developed sophisticated tracking systems and collaborative networks to monitor these celestial threats. While we cannot predict the exact timing of significant impacts, our technological capabilities continue advancing, allowing us to detect and potentially mitigate these cosmic dangers through international cooperation and innovative space programs.
Watch clip answer (00:08m)NASA
01:49 - 01:57
Why does the Moon appear larger when it's on the horizon compared to when it's high in the sky?
Despite over 2000 years of scientific inquiry dating back to Aristotle, there is still no definitive consensus on why the Moon appears larger on the horizon. Various theories have been proposed, including the Ponzo illusion and atmospheric effects, but none fully explain this optical phenomenon. Scientists understand that the Moon is not actually closer to Earth when it's on the horizon, yet our perception consistently makes it seem larger. This remains an active area of research as scientists continue investigating the complex interplay between atmospheric conditions and human visual perception to solve this enduring mystery.
Watch clip answer (00:06m)
NASA
01:08 - 01:14
Why does the Moon appear larger when it's positioned on the horizon compared to when it's high in the sky?
The Moon horizon illusion is likely explained by the Ponzo illusion, where our visual perception is influenced by our experience with distant objects. Throughout our lives, we observe that objects like clouds, planes, and ships appear to shrink as they move toward the horizon. However, the Moon maintains its actual size regardless of its position in the sky. To reconcile this inconsistency, our minds compensate by making the Moon appear larger when it's at the horizon. While this is a popular hypothesis among several theories involving atmospheric effects and cognitive biases, scientists are still conducting research to reach a definitive consensus on this fascinating optical phenomenon.
Watch clip answer (00:29m)NASA
00:38 - 01:08
Why does the Moon appear larger when it's on the horizon compared to when it's high in the sky?
The Moon appearing larger on the horizon is primarily an optical illusion rather than a physical phenomenon. Contrary to common assumptions, the Moon is actually about 1.5% farther away when on the horizon and atmospheric refraction slightly compresses its appearance rather than magnifying it. This same illusion affects constellations, which also appear larger near the horizon. The phenomenon has puzzled scientists since Aristotle's time, and while atmospheric effects have been ruled out as the primary cause, researchers continue investigating how our visual perception and psychological factors contribute to this enduring celestial mystery.
Watch clip answer (00:13m)NASA
00:25 - 00:38
Why does the Moon appear larger when it's positioned near the horizon compared to when it's higher in the sky?
The phenomenon of the Moon appearing larger near the horizon remains an unsolved scientific mystery that has puzzled experts for over 2,000 years, dating back to Aristotle's observations. Despite extensive research and ongoing scientific experiments, there is still no definitive consensus on the exact cause of this optical illusion. While scientists have proposed various theories including atmospheric effects and the Ponzo illusion (a visual perception phenomenon), the complete explanation continues to elude researchers, making it one of astronomy's most enduring puzzles.
Watch clip answer (00:17m)NASA
00:05 - 00:22