Category Astronomy

Why does the moon appear bigger near the horizon?

Sometimes, you may have watched the moon near the horizon and wondered “Why is the moon unusually bigger tonight?” Does the moon grow bigger near the horizon and shrink when it moves high up in the sky? This perception is called Moon illusion: Your brain is playing a trick on you.

Sky watchers have observed this phenomenon for thousands of years. The precise reason for the moon appearing to be expanding and contracting continues to puzzle scientists even today. But in general, our brain is tuned to think that objects near the horizon are (usually) more distant and larger than those overhead. But one thing is for sure – the moon isn’t changing size.

Here is an activity to test this: Take a sheet of paper and roll it up into a narrow tube. Point it at the rising moon, look through it and adjust the tube’s size until it’s slightly larger than the moon. Fix the tube using a tape so its size stays the same and look at the moon again a few hours later when it’s higher in the sky. You’ll see it fills the same space.

 

Picture Credit : Google

How do NASA and other space agencies communicate with spacecraft?

There are several spacecraft in space. But how do NASA and other space agencies communicate with these spacecraft?

Deep Space Network

Space agencies communicate with spacecraft using the Deep Space Network or DSN. The DSN is a collection of big radio antennas situated in different parts of the world. NASA’S DSN locations are near Canberra, Australia: Madrid, Spain, and Goldstone, California, the US. These sites are almost evenly spaced out meaning even as Earth turns, they never lose contact with the spacecraft.

ISRO, the Indian space agency’s DSN is located at Byalalu, near Bengaluru, Karnataka.

Space agencies use these DSN antennas to send instructions to the spacecraft while the spacecraft send images and other information to these antennas. The antennas also tell us about the location of spacecraft and how they are doing.

Connecting with the DSN antenna

Since spacecraft cannot carry a lot of weight as they need to leave Earth’s orbit and stay in space, all spacecraft are fitted with small antennas that can beam weak radio signals back to Earth. The farther away a spacecraft the larger the DSN antenna required to detect its signal and communicate with it. The largest antennas at each of NASA’S DSN sites is 70 mt in diameter.

Post connecting with an antenna

Once a spacecraft communicates with the DSN antenna, centres at each DSN site receive information. In the case of NASA, these sites send the information to the Space Flight Operations Facility at the Jet Propulsion Laboratory in Pasadena, California. Here, photos and other data are processed and shared with scientists and the rest of the world.

 

Picture Credit : Google

What is the Hayabusa-2 mission?

The six-year-old Ryugu mission came to an end for Japan’s Hayabusa-2 spacecraft when it brought back a capsule of samples from the asteroid on December 6. The capsule landed near Woomera in South Australia. After preliminary inspection, it was flown to the Japan Aerospace Exploration Agency (JAXA) research centre. The extremely high precision required to carry out the mission thrilled many in Japan. The project’s manager, Yuichi Tsuda of JAXA, called the capsule a “treasure box.” What’s the mission Hayabusa-2 all about and what’s special about Ryugu?

The unmanned Hayabusa-2 spacecraft was launched on December 3, 2014 to Ryugu, an asteroid more than 300 million km away from Earth. It is a successor to the Hayabusa mission, which returned asteroid samples from Itokawa in June 2010.

Hayabusa-2 arrived at the Ryugu asteroid in June 2018 after which it deployed two rovers and a small lander onto the surface. The asteroid’s extremely rocky surface forced the mission’s team to revise landing plans, and the spacecraft managed to collect data and soil samples in the more than one-year time it spent by Ryugu. In its first touchdown in February 2019, the spacecraft collected surface dust samples. In June 2019, Hayabusa-2 blasted a crater into the asteroid’s surface and then collected underground samples from the asteroid, a first for space history. In late 2019, Hayabusa-2 left Ryugu on its year-long journey to return the samples to Earth which ended on December 6, 2020.

How did the samples reach Earth?

As it approached Earth, approximately at 220,000 km from space, Hayabusa-2 released a capsule and fired its engines to push off in another direction. The 16 kg capsule entered the Earth’s atmosphere and landed inside the Woomera Range Complex in the South Australian outback using a parachute. A recovery team collected the pan shaped capsule, about 40 cm in diameter. The capsule contains soil samples taken from two different sites on asteroid Ryugu. Some gases might also be embedded in the samples. The preliminary inspection was done at a lab in Australia. The Hayabusa-2 team wanted the sample in Japan within 100 hours of its entry into Earth in order to keep the space rock pristine. So the capsule was taken on a nine-hour flight to the JAXA.

What is special about Ryugu?

Ryugu is a Near-Earth Asteroid (NEA) with orbits that pass dose by the Earth. It is classified as a potentially hazardous asteroid. Ryugu is an ancient fragment of a larger asteroid that formed in the cloud of gas and dust that spawned our solar system. It is an intriguing type of asteroid that’s rich in carbon, an element essential to life. The water composition of some asteroids is believed to be similar to Earth. By studying Ryugu, scientists hope to test this theory.

What can the asteroid samples tell us?

Asteroids orbit the Sun but are much smaller than planets. Scientists believe asteroids are made of the same stuff that went into forming the planets such as Earth They are among the oldest objects in the solar system and therefore may contain dues to how Earth evolved.

Scientists say the samples, especially those taken from under the asteroids surface contain data from 4.6 billion years ago unaffected by space radiation and other environmental factors. They are particularly interested in studying organic materials in the samples to learn about how they are distributed in the solar system and if or how they are related to life on Earth. The samples may help explain the origins of the solar system and how water helped to bring life to Earth. Fragments brought back from Ryugu can also tell its collision and thermal history.

Why is the mission such a big deal for Japan?

The first Hayabusa spaceship’s return was considered a miracle, given the troubles it encountered. JAXA’S subsequent Venus and Mars missions also were flawed. According to the Hayabusa-2 team, it used all the hard lessons learnt from the earlier missions to accomplish a 100 times better than “perfect outcome.

What is next for Hayabusa-2?

About an hour after the sample capsule separated from Hayabusa-2, the spacecraft was sent on another mission to the smaller asteroid. 1998KY26. That is an 11-year journey one way. The mission is to study possible ways to prevent big meteorites from colliding with Earth. Between 2021 and 2026, the spacecraft will also conduct observations of exoplanets.

As for the samples, some will be shared with NASA and other international scientists. About 40% of them will be stored for future research.

 

Picture Credit : Google

Why has Mars been chosen for human colonization?

For a planet to be habitable for humans, 1) it should be at a safe distance from the Sun – should be neither too hot, nor too cold; 2) it should contain liquid water, and 3) it should have a protective atmosphere that keeps the Sun’s radiation out. There is only one planet in the solar system that satisfies all these conditions and that planet is Earth. The next best option is Mars.

Mars has many advantages. It is very close to Earth – humans can reach the Red Planet in less than six months from Earth.

A Martian day is just over 24 hours long, roughly equivalent to a day on Earth. Mars has an atmosphere (though a thin one) that offers protection from cosmic radiation and solar radiation. Gravity on Mars is 38% that of Earth, which is believed by many to be sufficient for the human body to adapt to.

Evidence suggests that water may exist in the subsurface all over Mars. With help from technology, humans can survive on Mars, whereas the survival chances are slim on other planets and their moons.

 

Picture Credit : Google

Which is the outer part of the sun’s atmosphere, at hundreds of degrees higher temperature than the surface?

Our Sun is surrounded by a jacket of gases called an atmosphere. The corona is the outermost part of the Sun’s atmosphere.

The corona is usually hidden by the bright light of the Sun’s surface. That makes it difficult to see without using special instruments. However, the corona can be seen during a total solar eclipse.

The corona reaches extremely high temperatures. However, the corona is very dim. Why? The corona is about 10 million times less dense than the Sun’s surface. This low density makes the corona much less bright than the surface of the Sun.

The corona’s high temperatures are a bit of a mystery. Imagine that you’re sitting next to a campfire. It’s nice and warm. But when you walk away from the fire, you feel cooler. This is the opposite of what seems to happen on the Sun.

Astronomers have been trying to solve this mystery for a long time. The corona is in the outer layer of the Sun’s atmosphere—far from its surface. Yet the corona is hundreds of times hotter than the Sun’s surface.

A NASA mission called IRIS may have provided one possible answer. The mission discovered packets of very hot material called “heat bombs” that travel from the Sun into the corona. In the corona, the heat bombs explode and release their energy as heat. But astronomers think that this is only one of many ways in which the corona is heated.

 

Picture Credit : Google

What is your weight on the Moon?

If last week’s story on the birth of the Moon fascinated you here’s another quick fact about the Moon that is sure to grab your attention – your weight on the Moon would be much less compared to that on Earth! Yes, that’s true. Here’s why.

It all comes down to gravity

Your weight is a measure of the amount of gravity exerted on your body. Since gravity on each of the planets and space bodies is different your weight at any two places is bound to be different.

The gravity of an object is determined by its mass and size. Since the Moon is considerably smaller than Earth in mass, the gravity exerted on your body on the Moon is also much less – one-sixth that of Earth to be precise. However, even if you go to the Moon, only your weight will change, while your mass will remain the same as that on Earth. Actually, your mass anywhere in the universe is pretty much the same.

That makes your weight…

When you land on the Moon’s surface, your weight would be one-sixth of your current weight here.

For example, if you weigh 60 kg on Earth, your weight on the Moon’s surface would be about 10 kg.

 

Picture Credit : Google