aAstronomy and cosmology can feel disconnected from everyday reality. But what if we could take a 23rd century spaceship tour through the Milky Way and experience the universe like an Earth-bound tourist visiting exotic destinations? What will we see from our window?
Although physicists enjoy speculating about warp drives, or using wormholes to jump between locations, there is no way to travel faster than light at present. So we assume an imaginative ability to do this – but beyond that, everything we encounter on our journey is based on the best current theories.
Pass other investigations
When we exit the solar system and enter interstellar space, we will initially stop side by side Pioneer 11, one of the first probes to leave our planetary neighborhood. There is no sign “You are leaving the solar system” – but the border is the limit of a solar phenomenon. The Sun emits energetic particles that remove interstellar gas and dust. This no longer occurs at about 90 times Earth’s distance from the Sun.
Many probes have successfully exited the solar system. To the viewer, they look the same: a large radio dish bolted to a group of metal boxes. But the most interesting aspect lies in the attempts to communicate with passing alien garbage collectors. We can look at the golden discs On board Voyagers 1 and 2, which were launched in 1977 to study exoplanets. Or we could unpack the interstellar version of a high school time capsule on the 2006 New Horizons mission to Pluto and beyond… but we arrive alongside Pioneer 11, which along with its twin Pioneer 10 carries a mysterious gold-plated plaque.
Parts of the image are clear and straightforward: it shows two naked humans, with the probe at the same scale, and a map of the solar system. But what do you think of three small vertical lines above one horizontal line to the right of the female figure? Or a starburst effect that fills half the board?
The concept behind this is Conveying messages through scientific symbolism It was hoped that foreigners would understand it. The set of lines (representing the binary) gives the woman’s height, thanks to information extracted from the pair of linked circles (representing a process undergone by hydrogen atoms) at the top of the panel.
As for this stellar explosion, it precisely determines the location of the Earth. Each line represents the distance and direction of a series of pulsars – collapsing stars that release regular blasts of electromagnetic energy. The timing, shown in binary numbers on each line, indicates the frequency of the pulsar, based on the timing indicated by the hydrogen diagram. Some worry that this map opens us up to an alien invasion. Fortunately, some of the pulsar data is a little off. Even if accurate, this is a message in a bottle on a galactic scale, and it is unlikely to be found.
Stars Nursery
Leaving Pioneer behind, we traveled to the Orion Nebula. Of land, this forms part of The familiar constellation Orion, the Hunter. However, we have to remember that the apparent connection between the stars of the constellation is an illusion: they are not connected in reality. For example, Alnilam, the middle star of Orion’s Belt, is about 1,342 light-years from Earth, while Bellatrix, to the top right of Orion’s main stars, is only 245 light-years away. A light-year is the distance light travels in one year — about 5.9 trillion miles (9.5 trillion kilometers).
From Earth, the nebula looks like a small, mysterious patch in Orion’s sword, about 1,500 light-years away. This is where new stars are born from dust and gas, and is the closest nursery known to us. It is about 20 light-years across and contains nearly 1,000 new stars forming. that it Slow processThe particles that make up the cloud – mostly hydrogen atoms – are slowly pulled together by gravity. As they get ever closer, the temperature of the atoms rises, and with enough matter, the pressure and heat become so intense that nuclear fusion begins.
The young star begins converting hydrogen into helium, releasing energy in the process. The stars must be massive for this to happen. Our Sun, for example, is an average star, containing 99.8% of the matter in the solar system, and fusing about 600 million tons of hydrogen every second.
Other worlds
Our next stop is a protoplanetary disk: a rotating disk of dense gas surrounding a young star. In general, matter in the universe revolves around it. Because the clouds of gas and dust that give rise to stars are not evenly distributed, matter begins to rotate as gravity pulls it inward. Just as a skater’s rotation accelerates when he pulls his limbs, thanks to the conservation of angular momentum (the gravity with which something rotates), so a star’s rotation accelerates as matter accretes.
The central star has so much gravity that it remains spherical, but the material off-center flattens out to form a rotating disc, just as a ball of pizza dough does as it spins. In both cases, there is gravity toward the center, but not at a 90 degree angle toward the rotation, resulting in flattening. The material in the disk eventually coalesces due to gravity, producing planets.
On our tour, we can now visit exoplanets – more than 5,000 of which have been discovered by 2020. Trappist-1e is one of the most likely sites for life since discoveries in the early 2000s. It is rocky and similar to Earth in size. Although it is not confirmed in the 2020s, it appears to contain liquid water and an Earth-like atmosphere. It is recognized that its relationship with its star is not similar to its relationship with Earth: it completes its orbit in six days, as it is located at a distance approximately 15 times closer to its star than Mercury is to the sun. However, it is a very low-energy star, making Trappist-1e a potential home for life.
Supernova
Our next destination neighborhood certainly won’t be habitable for long: Betelgeuse, the bright red star to the upper left of Orion. In the 2020s, it was known that this giant red giant would go supernova within the next 100,000 years. We’re lucky, our imaginary spacecraft has arrived just as Betelgeuse is undergoing this cataclysmic change.
A supernova is a massive stellar explosion. From Earth, this means that some previously invisible stars are glowing brighter — hence the term “nova,” from the Latin for “new.” Betelgeuse has always been visible, but it’s about to get even brighter. We are running out of fusible materials. As heavier elements form, there comes a point when fusion consumes more energy than the star can supply and it extinguishes. Atoms heavier than iron cannot be produced in this way.
Until now, the energy of the nuclear reaction had been blowing up the star. Now, its interior is collapsing to form a neutron star — so dense that a teaspoon has a mass of about 100 million tons. When this core collapses, it bounces back, blowing away the star’s outer layers, providing much of the energy with which heavier elements are formed. Over the centuries, those outer layers will form a different type of nebula — a glowing remnant, like the Crab Nebula.
milky way
Our last stop before returning home enables us to see our galaxy, the Milky Way. This can be partially seen from the ground, but is difficult to see in built-up areas due to light pollution. In the dark sky, it appears as an arc of mysterious light. What we see from the house is the view from the inside. But here, from the outside, we see it in all its glory.
In the 2020s, we had never seen the Milky Way from the outside, but it was known to be a massive spiral galaxy about 100,000 light-years across, with a central band of densely packed stars. Despite being just one of about 200 billion galaxies located within the boundaries of the observable universe, the Milky Way is home to about 100 billion stars.
Although we can’t see something as small as the Sun from here, we can position it roughly near the edge of one of the outer spiral arms.
back to home
With the last jump, we return to Earth. It’s very small from the perspective of the galaxy, let alone the universe. However, this is a special place. Planets like ours, which have plenty of things suitable for life, are rare. A whole host of features have come together.
Earth is located in the “Goldilocks zone” – neither too hot nor too cold for liquid water, which appears to be essential for life. Our unusually large Moon stabilizes Earth’s orbit, and Earth’s active surface, a result of the Moon’s formation, helps keep our environment in balance. We have a stable star, as well as a strong magnetic field and an ozone layer that protects Earth from deadly solar radiation. Some say that land is nothing special. But it is, and we have to keep it that way.
