Category Astronomy

The short answer is that it takes sunlight an average of 8 minutes and 20 seconds to travel from the Sun to the Earth.

If the Sun suddenly disappeared from the Universe (not that this could actually happen, don’t panic), it would take a little more than 8 minutes before you realized it was time to put on a sweater.

Here’s the math. We orbit the Sun at a distance of about 150 million km. Light moves at 300,000 kilometers/second. Divide these and you get 500 seconds, or 8 minutes and 20 seconds.

You probably know that photons are created by fusion reactions inside the Sun’s core. They start off as gamma radiation and then are emitted and absorbed countless times in the Sun’s radiative zone, wandering around inside the massive star before they finally reach the surface.

What you probably don’t know, is that these photons striking your eyeballs were ACTUALLY created tens of thousands of years ago and it took that long for them to be emitted by the sun.

Once they escaped the surface, it was only a short 8 minutes for those photons to cross the vast distance from the Sun to the Earth.

 

Picture Credit : Google

NASA’s Viking 1 lander first showed humans what a sunset looked like on Mars in 1976. Several more Red Planet robots have since sent back a variety of views of Martian sunrises and sunsets.

Some color-corrected, blue-hued images preview what human Mars explorers might one day see while relaxing after a hard day’s work on the fourth planet.

Because Mars is farther from the Sun than Earth, the Sun appears only about two-thirds the size we see when we watch sunsets here on Earth.

Just as colors are made more dramatic in sunsets on Earth, Martian sunsets would appear bluish to human observers watching from the red planet. Fine dust makes the blue near the Sun’s part of the sky much more prominent, while normal daylight makes the Red Planet’s familiar rusty dust color more prominent.

 

Picture Credit : Google

You wouldn’t be able to walk on Jupiter, Saturn, Uranus or Neptune because they have no solid surface!

The strength of the gravitational field of the body also plays a role: too weak a gravitational field rules out walking, in the sense of taking strides. We know what walking was like on the Moon. It was funny-looking, but definitely walking. But our Moon, with only 1/6 Earth’s surface gravity, has the strongest surface gravity among the other moons of the Solar System. (Our Moon is composed mostly of rock, while all the other moons are primarily ices, and therefore much less dense.) With a weaker gravity, walking would be even stranger, and slower, but at some point, nothing like steps could happen. Where to draw the line? What is meant by “walking”? With 1/10 of our Moon’s gravity, is it walking?

The surface gravity of a body depends on both its mass and on its radius: it is proportional to the mass divided by the square of the radius. Thus, a smaller body of denser material may have a higher surface gravity than one of lighter material.

On most asteroids and smaller moons, the gravity is just too low—it wouldn’t be walking. Some medium-sized moons may be border cases though.

 

Picture Credit : Google

In space, no one can hear you scream. This is because there is no air in space – it is a vacuum. Sound waves cannot travel through a vacuum.

‘Outer space’ begins about 100 km above the Earth, where the shell of air around our planet disappears. With no air to scatter sunlight and produce a blue sky, space appears as a black blanket dotted with stars.

Space is usually regarded as being completely empty. But this is not true. The vast gaps between the stars and planets are filled with huge amounts of thinly spread gas and dust. Even the emptiest parts of space contain at least a few hundred atoms or molecules per cubic metre.

Space is also filled with many forms of radiation that are dangerous to astronauts. Much of this infrared and ultraviolet radiation comes from the Sun. High energy X-rays, gamma rays and cosmic rays – particles travelling close to the speed of light – arrive from distant star systems.

 

Picture Credit : Google

The seventh planet from the Sun with the third largest diameter in our solar system, Uranus is very cold and windy. The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates at a nearly 90-degree angle from the plane of its orbit. This unique tilt makes Uranus appear to spin on its side, orbiting the Sun like a rolling ball.

The first planet found with the aid of a telescope, Uranus was discovered in 1781 by astronomer William Herschel, although he originally thought it was either a comet or a star.

Uranus is one of two ice giants in the outer solar system (the other is Neptune). Most (80 percent or more) of the planet’s mass is made up of a hot dense fluid of “icy” materials—water, methane and ammonia—above a small rocky core. Near the core, it heats up to 9,000 degrees Fahrenheit (4,982 degrees Celsius).

Uranus is slightly larger in diameter than its neighbor Neptune, yet smaller in mass. It is the second least dense planet; Saturn is the least dense of all.

Uranus gets its blue-green color from methane gas in the atmosphere. Sunlight passes through the atmosphere and is reflected back out by Uranus’ cloud tops. Methane gas absorbs the red portion of the light, resulting in a blue-green color.

 

Picture Credit : Google

There are dozens upon dozens of moons in the Solar System, ranging from airless worlds like Earth’s Moon to those with an atmosphere (most notably, Saturn’s Titan). Jupiter and Saturn have many moons each, and even Mars has a couple of small asteroid-like ones. But what about Venus, the planet that for a while, astronomers thought about as Earth’s twin? The answer is no moons at all. That’s right, Venus (and the planet Mercury) are the only two planets that don’t have a single natural moon orbiting them.

Because Mercury is so close to the Sun and its gravity, it wouldn’t be able to hold on to its own moon. Any moon would most likely crash into Mercury or maybe go into orbit around the Sun and eventually get pulled into it.

“Most likely, Venus was slammed early on and gained a moon from the resulting debris. The satellite slowly spiraled away from the planet, due to tidal interactions, much the way our Moon is still slowly creeping away from Earth,” Sky and Telescope wrote of the research.

 

Picture Credit : Google