# Speed of light: it can be slow too

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1922

What if scientists say that the speed of light is slow. Would you believe that statement? Obviously, you will question your knowledge. We all have studied that light has the fastest speed than any other thing.

Photons- particles which combine to form light. In vacuum having no obstacle (such as atmosphere etc.), a single photon can travel 299,792 kilometers per second or 186,282 miles per second. In terms of hours, these values would be 1.079 billion kph or 670.6 mph. This is a very fast speed, even nobody can imagine how fast a photon can travel.

You would be thinking that then how can scientists think that the speed of light is slow?

However, while communicating among planets light can be very slow. NASA’s planetary scientist James O’Donoghue made different animations which show that light travels very slow while communicating with other planets. At first, O’Donoghue created animations about the vanishing rings of the planet Saturn. NASA has released these animations. Then O’Donoghue released the animations to depict that speed of light can be frustratingly slow at times. He presented three different animations to show the other image of the speed of the light.

The first scenario O’Donoghue presented is about the photon which travels around the Earth. As we know that Earth is 24,901 miles around at its center. In each second a photon can complete 7.5 rounds (eliminating all the obstacles like air). These rounds are very less to fulfill the statement that light can travel very fast or light has the fastest speed.

O’Donoghue then measured the speed of light when it travels from Earth to the moon or vice versa. Moon is almost 384,400 kilometers or 238,855 miles far from the Earth. The moonlight we see is 1.255 seconds (2.51 second for the round trip) old, which questions the fastness of the speed of the light. Hence, the animation says that light can be slow too. It is believed that this time duration is increasing as the Moon is moving away from the Earth about 3.8 centimeters or 1.5 inches every year.

The third animation shown by O’Donoghue is between Mars and Moon. Spacecraft like InSight probe on Mars is used to get the data from Mars. Scientists can do this at the speed of light. They have to send the command before time so that they do not miss the target due to the slow speed.

Closest approach- event occurs once in two years. In this event, both planets have the minimum distance i.e. 54.6 million kilometers or 33.9 million miles away. Light covers this distance in 3 minutes and 2 seconds. While normally to cover 158 million miles light takes 28 minutes and 12 seconds to cover a round trip.