The Earth, the Sun and the Moon

The fastest thing in the Universe

                                    The most colorful view of the Universe recorded by the Hubble Space Telescope

The universe itself has a cosmic speed limit. That is, there is a limit to how fast objects can travel through space. This speed limit is about 186,000 miles per second, and there is only one thing in the world that travels at this speed: light. Light is the fastest known thing in the universe, and so the limit of cosmic velocity is called the speed of light. No matter how hard you try, you can never exceed the speed of light. Like gravity, the limit of cosmic velocity is a fixed law of nature that cannot be violated. Whether it comes from a star or your cell phone lens, each beam of light will travel at 186,000 miles per second.

The fastest known planet

                                    Planet Kepler-78b

For the past 30 years, scientists have discovered thousands of planets orbiting stars outside our solar system. Many of these worlds are very different from those orbiting our Sun. Regardless of the type of planets orbiting a star, one thing they all have in common is how their orbital velocity relates to the distance between them and their star. Planets orbiting near their star will complete an orbit faster than planets orbiting farther away. Mercury is the fastest planet in our solar system, completing one rotation every 88 days. This may seem fast, but it’s nothing compared to some other planets in our galaxy. The fastest planet ever discovered was found in 2013 by NASA’s Kepler Space Telescope. Named Kepler-78b, it orbits its star just 900,000 miles away. By comparison, Mercury orbits the Sun 36 million miles away. With a very short distance between Kepler-78b and its parent star, the planet orbits the Sun at extreme speeds. It takes just 8.5 hours for Kepler-78b to complete an orbit around its star. Imagine living on a planet where time is only 8.5 hours. So far, no other planet has been found with a shorter orbital period, making Kepler-78b the fastest known planet in the universe.

The fastest known star

                                    US-708 Star

It may not seem like our point of view here on Earth, but the Sun actually crosses space. Like the planets orbiting the Sun, the Sun orbits the center of the Galaxy. Currently, the entire solar system is moving in space at 448,000 miles per hour. This may seem fast, but the Sun takes 230 million years to complete an orbit because of how gigantic the Galaxy is. Compared to some other stars out there, our Sun is relatively slow. The fastest known star in the universe is near the center of the Galaxy. It is called US-708 and has been measured to travel at a speed of 2.7 million miles per hour. When scientists first discovered the US-708 and measured its speed, they believed it was orbiting a black hole. The gravitational pull of the black hole would be so strong that it would have accelerated the US-708 at tremendous speeds. However, later observations revealed that the US-708 could indeed have been propelled at its current speed by an exploding star. US-708 was once part of a binary star system, where its companion star eventually exploded in a supernova. The resulting explosion was so energetic that it pushed US-708 to become the fastest known star in the universe.

The fastest man-made object

                                    The Parker Solar Probe

We’ve talked about some of the fastest things in the universe, but how does humanity compare? What’s the fastest thing humans have ever created? As one would expect, the fastest man-made objects are generally spaceships. Currently, the fastest man-made spacecraft is the Parker Solar Probe, a spacecraft launched by NASA in 2018 to fly closer to the Sun than any other spacecraft before it. When NASA launched the Parker Solar Probe, it reached a speed of 39,500 miles per hour. On its way to the Sun, the Parker Solar Probe made repeated flights to the planet Venus to increase its speed, using what is called gravity assistance. As of February 2020, the Parker Solar Probe has become the fastest man-made object in history, reaching speeds of 330,000 miles per hour. It’s fast enough to orbit the Earth 13 times an hour! For humanity, this is truly a remarkable achievement. However, even at this speed, the Parker Solar Probe has achieved only 0.05% light speed. Aidan Remple April 12, 2022 in Science