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Новости во астрономијата за септември 2018

30/9/2018

Најинтересните вести кои можеби ги пропуштивте од полето на астрономијата и сродните науки.

- Први фотографии од површина на астероид

- Џозелин Бел ќе ја донира наградата од 3 милиони долари

- Поларниот шестоаголник на Сатурн

- Објавен првиот астро-патник околу Месечината

- Прстени од црни дупки

Следете нè и понатаму.

Небото во октомври:

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Ceres the Non-planet Planet

27/9/2018

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When thinking about where life could exist elsewhere in our own Solar neighborhood the debate is often centered around the oceans of Europa, oceans of Titan, the surface of Mars and the clouds of Venus, but a relatively not discussed body in our Solar System could actually hold a genuine possibility that life exists or may have existed at one point within it. It's not what you might expect, however when we think of life, we think of large planets, plentiful oceans, well as it turns out this body may just prove that life is a bit more prevalent and resistant than that it is. Ceres is a dwarf planet and an asteroid, the largest celestial body located within the main asteroid belt located between the orbits of Mars and Jupiter. Comprised of mostly rock and ice this little planet has recently been found to have key ingredients for organic life to emerge.

Image of the dwarf planet Ceres © NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / Justin Cowart

The name Ceres originates from the Roman goddess of Agriculture, with that said, you shouldn’t imagine forests, crops, and nature is a little bit of an exaggeration for this celestial body, but Ceres is certainly diverse, unique and very interesting. So let's dive into its frozen oceans as we search for life on the dwarf planet located at just less than 2.8 astronomical units, one astronomical unit – AU being the distance between Earth from the Sun. From our local star, Ceres is located within the asteroid belt. Ceres is essentially the largest of the large asteroids within the belt, hence why it tows the line between asteroid and planet.

The intriguing brightest spots on Ceres lie in a crater named Occator © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

It was first discovered in 1801 by astronomer Giuseppe Piazzi at the astronomical observatory of Palermo. In the years leading up to this it was theorized that a planet like Ceres would exist between Mars and Jupiter as part of the now disproven Titius-Bode law. The law stated that each planet moving further away from the Sun would have to orbit at twice the distance of the previous one, meaning the various planetary orbits in the Solar System were increasing in radius exponentially. A discredited theory now, but it led astronomer Johannes Kepler to notice the gap between Mars and Jupiter and he theorized something undiscovered may lie there. This lucky coincidence led Hungarian astronomer Franz Xaver von Zak to assemble a team of 24 astronomers nicknamed the Celestial Police to search the area for a planetary body in 1800 the team found several large asteroids that we now know to be in the asteroid belt. But it was Giuseppe Piazzi an Italian astronomer who discovered the dwarf planet of Ceres by accident. He had been searching for star-like objects when he observed Ceres for the first time and although he initially thought he'd found some sort of comet, further observations eventually ended up with him labeling his discovery as a planet and being invited to join the Celestial Police before illness meant he could no longer observe the skies. Estimates of this celestial body didn't really get much within the correct bounds some theorized it to be as small as 200 kilometers in diameter whereas others placed it around Pluto size at 2,500 kilometers wide.

Size comparison of our Moon and all the dwarf planets

We now know Ceres’ size to be about 945 kilometers in diameter meaning that Ceres is a comparative size to the top to bottom length of the United Kingdom. It takes 1681 days to orbit the Sun, just over four and a half Earth years. Ceres origin is still up for debate, we predict it to be roughly four and a half billion years old and we theorize it might be a surviving protoplanet also known as a planetary embryo. It’s an asteroid like body that rams into other asteroids to form terrestrial planets. Most of the inner Solar System protoplanets are believed to have been either merged into planets or ejected from the solar system altogether by Jupiter's orbit and gravity. Ceres seems to have survived these eventualities relatively unscathed. Other theories however state that Ceres was actually formed within the Kuiper belt before migrating nearer the Sun via various large gravitational influences this theory holds way given the presence of ammonia salts detected in Ceres’ Occator crater and also Ceres believed formation under colder conditions than most planets and asteroids lends credibility to this theory, meaning that the dwarf planet was formed beyond Jupiter's orbit. For its competition Ceres was originally considered a planet for about 50 years before being reclassified by early astronomers in the mid-1850s after the discovery of other asteroids in its neighborhood. It’s now considered a dwarf planet, minor planet or large asteroid. It was actually Ceres and its neighbors that were crucial in the discovery of the asteroid belt. Most of these asteroid rocks were originally thought to be like stars, but following the discoveries of these asteroids, astronomers realized they fell under a new classification. One year after Ceres discovery in 1802 with the discovery of the second large asteroid Pallas, William Herschel designated the term asteroid which literally means star-like. Under the more recent minor planet designation system, Ceres full name is actually ‘1 Ceres’ followed by ‘2 Pallas’, ‘3 Juno’ and ‘4 Vesta’, numbered in the order of their discovery. In 2006 Pluto who is reclassified as a dwarf planet thanks to the discovery of Eris, another dwarf planet a year earlier. This put Ceres up for debate - being a lot smaller. On the 24th of August 2006 a planetary definition was adopted that stated that a planet had to dominate its orbit, which ruled out asteroids from the get-go as no asteroid in the belt actually cleared out its own orbital path, instead being part of the larger asteroid belt it too became a dwarf planet.

Occator crater in exaggerated colors © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA /Roman Tkachenko

What about the planet itself? Well we know Ceres is made of mostly ice and rock there is a rocky interior with an icy exterior. We have interestingly observed what could be the remnant of an ocean that once held liquid water, an essential building block for life as we know it. On the surface ice mixes with various minerals and you can even find iron rich clay on surface. Ceres' surface is relatively warm for an asteroid with an average surface temperature of 235 Kelvin (-38° C). About five years ago in January 2014 we detected water vapor in several regions. The water vapor comprises more of Ceres’ external makeup than we realized. This could be the result of outgassing or from a unique type of volcano called a cryovolcano. This outgassing is actually a common feature of a comet. Internally Ceres’ mantle which is about 100 kilometers thick could contain up to 200 million cubic kilometers of water which is more than all the fresh water on Earth. Aside from all that, some other interesting things about the planet is that the mass accounts for approximately 1/3 of the entire asteroid belt’s total mass and it is the only belt object to be rounded by its own gravity. It is also the only classified dwarf planet inside the orbit of Neptune and it's the 33rd largest celestial body in the solar system. But what makes this planet so interesting is its composition lends itself to the formation of life as we know it and so perhaps there is some form of life that has existed or currently exists near its surface.

Ahuna Mons imaged by the Dawn spacecraft © NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

In another of Ceres craters some organic materials were discovered, they are a key ingredient for life to form and thrive, but what made it more interesting was the fact that these more organic materials seem to be endogenous, meaning they originated from inside the planet itself. Scientists were very pleased with this discovery but something a bit more well-known that brings the discussion of life to the table are the famous bright spots, a seemingly unique feature to Ceres. A year after detecting water vapor, NASA's Dawn spacecraft went to observe Ceres and entered its orbit in March 2015 this was when its cratered surface was discovered and two very distinct bright spots were observed inside one such crater. Though NASA often dismissed this as reflectivity for glaciers it was initially thought to be a cryovolcano. A concept mentioned earlier cryovolcanoes are a type of volcano that spirit iced water methane and ammonia instead of magma. 18 months after the bright spot discovery dawn scientists documented a mountain on Ceres named Ahuna Mons this mountain is fairly unique as the dwarf planet doesn't seem to have any other mountains. What it did have was bright streaks similar in appearance to the bright spots down his side. This pointed to the theory that Ahuna Mons is a cryovolcano. Near infrared spectra of the planet also suggested that the geologic activity may have something to do with the spots, now however NASA scientists believe the spots may have been caused by a form of brine related to reflective ammonia salts on the surface. It may well be the cryovolcano theory as the bright spots seemed to shine when they are even not facing the Sun. Some theorize that life may have existed in the past in the liquid water oceans of Ceres but not anymore. Even if it is devoid of life now the planet does boast favorable conditions for life as we know it water on the surface vapor and the 20% carbon mass could provide the right conditions for organic chemistry but for now we really don't know.

Habitability is no guarantee of presence of life. Just because Ceres is habitable and suitable for life and primitive life, that doesn't mean a single microorganism has to exist at all on a surface perhaps the shiny spots to open the door to the possibility of some form of life but until more studies are done we cannot confirm nor deny this if life in any form actually does exist on Ceres. However then it's incredibly likely they involved independently to earth and if so the process of life formation may be more robust and common than we expected. If we can find life prevalent and resilient enough to survive for billions of years on the surface of an asteroid then who knows what earth-like planets such as Kepler 22b could hold.

Artist’s impression of Kepler 22b (c) NASA/Ames/JPL-Caltech

Life could be common, if Ceres has life against all odds then Jupiter's Europa stands a very good chance of having some form of life in its oceans and who knows what could be elsewhere in the solar system. Let's hope future observations of Ceres and such other places can reveal this possibility, because if so, it opens up the potential for an entire galaxy full of amazing very life for us to discover and learn from in all of its corners imagine the kind of knowledge such a library of interplanetary species would give us and unlocking all of their potential could begin with this remote tiny but brilliant celestial body that is the planet of Ceres.

Kristijan Shishkovski

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Први фотографии од површина на астероид

25/9/2018

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Од јапонското вселенско летало Хајабуса 2 кое е во орбита на астероидот Рјугу се испратија 2 сонди на самата површина. Сондите ги нарекуваат ровери бидејќи можат да ја менуваат локацијата скокаjќи од една позиција на друга. Роверите 1А и 1Б се наречени МИНЕРВА-II1 кои за викендот ги испратија првите снимки направени на површината од астероидот и делуваат спектакуларно. Роверите се со големина на фризби и тежат помалку од еден килограм.

Фотографија направена од роверот 1А во саботата на 22 септември со одблесок од сончевата светлина низ леќите (с) JAXA/Hayabusa 2

Горната фотографија е направена додека роверот 1А отскокнувал од површината. Ова е прв пример од сонда која слетала на астероид и може да ја менува позицијата со помош на реактивни мотори.

Уметничка претстава на малите ровери на површината на Рјугу (с) JAXA

Фотографија од роверот 1Б направена на стотина метри од површината на астероидот Рјугу пред слетувањето (с) JAXA/Hayabusa 2

Во иднина планирани се уште 2 слетувања, со германската сонда МАСКОТ на почетокот од октомври и МИНЕРВА-II чие слетување е планирано за наредната година.

Автор: Ивана Крстевска

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Новости во астрономијата за септември 2018

Ceres the Non-planet Planet

Први фотографии од површина на астероид

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