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How Big Is The Moon?

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The moon has a radius of 1,080-miles (1,737-kilometers). This means that the moon’s diameter is 2,159-miles (3,475-kilometers) across. For comparison, the diameter of Earth is 7,918-miles (12,742-kilometers). This shows that the moon is approximately a quarter the width of Earth. The moon’s size impacts specific processes on Earth, the most notable of which is the tides. The moon’s gravitational pull causes the oceans to bulge on either side. As the planet rotates, these bulges also rotate, causing the rise and fall of seawater. Gravitational force is dictated by the size and distance of objects, so if the moon were the size of Mars’s moons, Phobos and Deimos, it would not have as strong of a gravitational pull and thus would not affect the tides.

Compared To Other Objects in the Solar System

The moon has a diameter of 2,159-miles (3,475-kilometers)

It can be hard to visualize just how big celestial bodies are and the moon is no exception. Earth’s moon is fairly big in comparison to other moons in the solar system, but what exactly does that mean? The moon orbiting Earth is the fifth largest moon in the solar system. Moons larger than ours include, in decreasing order, Ganymede, Titan, Callisto, and Io. Even though Earth’s moon is not the biggest in the solar system, it is the largest when compared to the planet it orbits. The moon is also quite a bit bigger than the dwarf planet, Pluto which has a radius of 1,477-miles (2377-kilometers). This makes Pluto around 70% the size of Earth’s moon.

Compared to countries on Earth

Earth and moon
This image, which shows both the Earth and its moon, was taken by the Mars Reconnaissance Orbiter while orbiting Mars. Image credit: NASA

It still might be hard to visualize just how large the moon is when only comparing it to other celestial objects. Comparing the size of our moon to countries and continents on Earth might show more context into its sheer size. The United States of America has a diameter of 2,897-miles (4,662-kilometers), making it almost the same width as the moon. However, having the diameter of the moon only paints a part of the picture. To compare the moon’s size to the size of countries on Earth, the surface area is required. The moon’s surface area is 14.6-million square miles (38-million square kilometers). When compared again to the United States of America, the moon has approximately four times as much surface area. This is smaller than the continent of Asia (including Russia) which boasts a surface area of 17.2-million square miles (44.6 million square kilometers).

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An asteroid will whip by Earth tomorrow in one of closest approaches ever recorded

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An asteroid the size of a delivery truck will whip past Earth on Thursday night, one of the closest such encounters ever recorded.

NASA insists it will be a near miss with no chance of the asteroid hitting Earth.

The U.S. space agency said Wednesday that this newly discovered asteroid will zoom 3,600 kilometres above the southern tip of South America. That’s 10 times closer than the bevy of communication satellites circling overhead.

The closest approach will occur at 7:27 p.m. ET.

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Even if the space rock came a lot closer, scientists said most of it would burn up in the atmosphere, with some of the bigger pieces possibly falling as meteorites.

NASA’s impact hazard assessment system, called Scout, quickly ruled out a strike, said its developer, Davide Farnocchia, an engineer at the agency’s Jet Propulsion Laboratory in Pasadena, Calif.

“But despite the very few observations, it was nonetheless able to predict that the asteroid would make an extraordinarily close approach with Earth,” Farnocchia said in a statement.

“In fact, this is one of the closest approaches by a known near-Earth object ever recorded.”

Asteroid spotted by amateur astronomer in Crimea

Discovered Saturday, the asteroid known as 2023 BU is believed to be 3.5 to 8.5 metres across.

It was first spotted by Gennady Borisov, the same amateur astronomer in Crimea who discovered an interstellar comet in 2019.

Within a few days, dozens of observations were made by astronomers around the world, allowing them to refine the asteroid’s orbit.

The asteroid’s path will be drastically altered by Earth’s gravity once it zips by. Instead of circling the sun every 359 days, it will move into an oval orbit lasting 425 days, according to NASA.

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Nuclear-powered spaceships? U.S. plans for 2027

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WASHINGTON –

The United States plans to test a spacecraft engine powered by nuclear fission by 2027 as part of a long-term NASA effort to demonstrate more efficient methods of propelling astronauts to Mars in the future, the space agency’s chief said on Tuesday.

NASA will partner with the U.S. military’s research and development agency, DARPA, to develop a nuclear thermal propulsion engine and launch it to space “as soon as 2027,” NASA administrator Bill Nelson said during a conference in National Harbor, Maryland.

The U.S. space agency has studied for decades the concept of nuclear thermal propulsion, which introduces heat from a nuclear fission reactor to a hydrogen propellant in order to provide a thrust believed to be far more efficient than traditional chemical-based rocket engines.

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NASA officials view nuclear thermal propulsion as crucial for sending humans beyond the moon and deeper into space. A trip to Mars from Earth using the technology could take roughly four months instead of some nine months with a conventional, chemically powered engine, engineers say.

That would substantially reduce the time astronauts would be exposed to deep-space radiation and would also require fewer supplies, such as food and other cargo, during a trip to Mars.

“If we have swifter trips for humans, they are safer trips,” NASA deputy administrator and former astronaut Pam Melroy said Tuesday.

The planned 2027 demonstration, part of an existing DARPA research program that NASA is now joining, could also inform the ambitions of the U.S. Space Force, which has envisioned deploying nuclear reactor-powered spacecraft capable of moving other satellites orbiting near the moon, DARPA and NASA officials said.

DARPA in 2021 awarded funds to General Atomics, Lockheed Martin and Jeff Bezos’ space company Blue Origin to study designs of nuclear reactors and spacecraft. By around March, the agency will pick a company to build the nuclear spacecraft for the 2027 demonstration, the program’s manager Tabitha Dodson said in an interview.

The joint NASA-DARPA effort’s budget is US$110 million for fiscal year 2023 and is expected to be hundreds of millions of dollars more through 2027.

Reporting by Joey Roulette; Editing by Chizu Nomiyama and David Gregorio

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The green comet ZTF returns to the solar system 50,000 years later… and it will be visible from Earth

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For astronomy enthusiasts, February 1 is marked in red on their calendars. The reason: it is not every day that there is a chance to see a green comet.

In fact, it is the first time in 50,000 years that C/2022 ZTF will return to the solar system. And it will be early next month when it will reach its closest position to Earth.

Specifically, the green comet ZTF will pass 42 million light years from our planet. Experts are not 100 percent sure whether it will be visible from the surface without the use of any instrument. However, if we have specific astronomy binoculars or telescopes, we will be able to see it without any problem.

As usually happens in these cases, the best places to observe the comet, this one or any other, are places with little artificial light. That is to say, we should move away from urban centres and it is preferable to do so in the hours before dawn.

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Un cometa brillante, visto desde California.Getty

Why is comet ZTF green?

Comet ZTF has a brightness and a colour that, although not unique, is clearly distinctive. Its hue is due to the fact that it is composed, among other materials, of diatomic carbon.

When it comes into contact with sunlight, the decomposition of this element causes the gas to acquire this spectacular colour.

Comet ZTF was discovered in March 2022

Un telescopio apunta al cielo.
Un telescopio apunta al cielo.Getty

Frank Masci and Bryce Bolin of the Palomar Observatory in California were responsible for spotting the striking comet ZTF in the sky. It is so named because its discovery is part of the Zwicky Transient Facility surveillance programme, which uses the powerful Schmidt telescope at the facility.

Initially, the scientists responsible for the discovery thought it was an asteroid, but they quickly realised that this was not the case. Despite the striking colour of this comet, experts advise keeping expectations low. In any case, it is an event that has aroused great interest in the community.

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