Category Astronomy

April 12 was already a huge day in space history twenty years before the launch of the first shuttle mission. On that day in 1961, Russian cosmonaut Yuri Gagarin became the first human in space, making a 108-minute orbital flight in his Vostok 1 spacecraft.

In 1955, Gagarin was accepted to the First Chkalovsky Higher Air Force Pilots School in Orenburg. He initially began training on the Yak-18 already familiar to him and later graduated to training on the MiG-15 in February 1956. Gagarin twice struggled to land the two-seater trainer aircraft, and risked dismissal from pilot training. However, the commander of the regiment decided to give him another chance at landing. Gagarin’s flight instructor gave him a cushion to sit on, which improved his view from the cockpit, and he landed successfully. Having completed his evaluation in a trainer aircraft, Gagarin began flying solo in 1957.

On 5 November 1957, Gagarin was commissioned a lieutenant in the Soviet Air Forces having accumulated 166 hours and 47 minutes of flight time. He graduated from flight school the next day and was posted to the Luostari Air Base close to the Norwegian border in Murmansk Oblast for a two-year assignment with the Northern Fleet. On 7 July 1959, he was rated Military Pilot 3rd Class. After expressing interest in space exploration following the launch of Luna 3 on 6 October 1959, his recommendation to the Soviet space programme was endorsed and forward by Lieutenant Colonel Babushkin. By this point, he had accumulated 265 hours of flight time. Gagarin was promoted to the rank of senior lieutenant on 6 November 1959, three weeks after he was interviewed by a medical commission for qualification to the space programme.

 

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In astrophysics, spaghettification (sometimes referred to as the noodle effect) is the vertical stretching and horizontal compression of objects into long thin shapes (rather like spaghetti) in a very strong non-homogeneous gravitational field; it is caused by extreme tidal forces. In the most extreme cases, near black holes, the stretching is so powerful that no object can withstand it, no matter how strong its components. Within a small region the horizontal compression balances the vertical stretching so that small objects being spaghettified experience no net change in volume.

The way it works has to do with how gravity behaves over distance. Right now, your feet are closer to the centre of Earth and are therefore more strongly attracted than your head. Under extreme gravity, say, near a black hole, that difference in attraction will actually start working against you.

As your feet begin to get stretched by gravity’s pull, they will become increasingly more attracted as they inch closer to the centre of the black hole. The closer they get, the faster they move. But the top half of your body is farther away and so is not moving toward the centre as fast. The result: spaghettification!

 

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The ‘event horizon’ is the boundary defining the region of space around a black hole from which nothing (not even light) can escape. In other words, the escape velocity for an object within the event horizon exceeds the speed of light. The name arises since it is impossible to observe any event taking place inside it – it is a horizon beyond which we cannot see. 

When an item gets near an event horizon, a witness would see the item’s image redden and dim as gravity distorted light coming from that item. At the event horizon, this image would effectively fade to invisibility.

Within the event horizon, one would find the black hole’s singularity, where previous research suggests all of the object’s mass has collapsed to an infinitely dense extent. This means the fabric of space and time around the singularity has also curved to an infinite degree, so the laws of physics as we currently know them break down. 

The strength of a black hole’s gravitational pull depends on the distance from it — the closer you are, the more powerful the tug. But the effects of this gravity on a visitor would differ depending on the black hole’s mass. If you fell toward a relatively small black hole a few times the mass of the sun, for example, you would get pulled apart and stretched out in a process known as spaghettification, dying well before you reached the event horizon. 

 

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Astronomers have defined a new class of celestial objects called “ploonets,” which are orphaned moons that have escaped the bonds of their planetary parents.

Although there has yet to be a definitive detection of a ploonet orbiting a star, there are at least a few examples that might fit the bill. The evidence for these potential ploonets comes from perplexing exoplanetary observations that have yet to be adequately explained.

For instance, the researchers of the new paper describe how “moon-star collisions could explain the anomalous spectroscopic features of the stars Kronos and Krios (HD 240430 and HD 240429), which show deep traces of heavy elements.” This is because ploonets are likely made up of largely volatile material — which are light elements and compounds like hydrogen and water that rapidly evaporate — and because ploonets are located so close to their host stars, which exposes them to very strong stellar radiation.

According to the authors, this means that over millions of years, a ploonet will lose a significant chunk of its lighter elements, leaving behind a rather heavy-metal ploonet. If these metal-rich ploonets are then absorbed into their host star, they can produce observational signals that suggest the star instead devoured rocky planets, as may be the case with Kronos.

 

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A subsatellite is a natural or artificial satellite that orbits a natural satellite, i.e. a “moon of a moon”.

It is inferred from the empirical study of natural satellites in the Solar System that subsatellites may be elements of planetary systems. In the Solar System, the giant planets have large collections of natural satellites. The majority of detected exoplanets are giant planets; at least one, Kepler-1625b, may have a very large exomoon, named Kepler-1625b I. Nonetheless, no “moon of a moon” or subsatellite is known in the Solar System or beyond. In most cases, the tidal effects of the planet would make such a system unstable.

Terms used in scientific literature for moons of moons include “submoons” and “moon-moons”. Other terms that have been suggested include moonitos, moonettes, and moooons.

 

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Hayabusa 2 is a Japanese mission launched in December 2014 on a six-year mission to study the asteroid Ryugu and to collect samples to bring to Earth for analysis.

Hayabusa 2 was launched in December 3, 2014. The mission includes a main spacecraft, small rovers, a lander, and an impactor that will be launched into the asteroid’s surface to create an artificial crater. The spacecraft is expected to touch down on Ryugu multiple times starting in early 2019 to collect samples to bring to Earth in late 2020.

After launch, the spacecraft completed an initial checkout period by March 2, 2015 and then moved into its “cruising phase” toward asteroid Ryugu.

Less than a year later, on December 3, 2015, Hayabusa 2 carried out an Earth flyby at a range of 1,920 miles (3,090 kilometers) over Hawaii to increase the spacecraft’s velocity.

The spacecraft performed the first major firing of its ion engines between March 22 and May 5, 2016. It conducted a shorter (3.5 hour) firing on May 20, 2016 to adjust its trajectory.

Hayabusa 2 arrived at asteroid Ryugu in June 2018.

 

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