“Over the past 30 years, astronomers have gone from zero known extra-solar planets to thousands. Periodic changes in a star’s motion or regular brightness dips give them away. Thanks to these techniques, we’ve revealed the masses and radii of worlds nearby and thousands of light years away. Over 200 are Earth-sized, with many residing in the so-called habitable zone around their stars. Yet with everything we’ve found, there are no potentially habitable Earth-like worlds around Sun-like stars.”
One of the greatest success stories over the past 30 years is the giant leap forward we’ve taken in understanding what worlds lie beyond our Solar System. We’ve gone, in that time, from exactly zero known planets beyond our Solar System to thousands. We’ve found worlds far larger than Jupiter, some of which revolve at distances interior to even Mercury’s orbit. We’ve found planets around blue supergiants and red dwarfs. And we’ve discovered small worlds, some of which are even smaller than Earth. Some of them even occur in the so-called habitable zone of their stars.
The Aurora and the Sunrise : On the International Space Station (ISS), you can only admire an aurora until the sun rises. Then the background Earth becomes too bright. Unfortunately, after sunset, the rapid orbit of the ISS around the Earth means that sunrise is usually less than 47 minutes away. In the featured image, a green aurora is visible below the ISS – and on the horizon to the upper right, while sunrise approaches ominously from the upper left. Watching an aurora from space can be mesmerizing as its changing shape has been compared to a giant green amoeba. Auroras are composed of energetic electrons and protons from the Sun that impact the Earth’s magnetic field and then spiral down toward the Earth so fast that they cause atmospheric atoms and molecules to glow. The ISS orbits at nearly the same height as auroras, many times flying right through an aurora’s thin upper layers, an event that neither harms astronauts nor changes the shape of the aurora. via NASA
This Is Why Sputnik Crashed Back To Earth After Only 3 Months
“But for the 25,000+ other satellites in low-Earth orbit, there is no controlled re-entry coming. Earth’s atmosphere will take them down, extending far beyond the artificial edge of space, or Kármán line, that we typically draw. If we were to cease launching satellites today, then in under a century, there would be no remaining trace of humanity’s presence in low-Earth orbit.
Sputnik 1 was launched in 1957, and just three months later, it spontaneously de-orbited and fell back to Earth. The particles from our atmosphere rise far above any artificial line we’ve drawn, affecting all of our Earth-orbiting satellites. The farther your perihelion is, the longer you can remain up there, but the harder it becomes to send-and-receive signals from here on the surface. Until we have a fuel-free technology to passively boost our satellites to keep them in a more stable orbit, Earth’s atmosphere will continue to be the most destructive force to humanity’s presence in space.”
On October 4th, 1957, the world changed forever with the launch of Sputnik 1. One of the common questions that astronomers get asked is whether we can still see it or not. The answer surprises most people: not only can’t we see it, but it crashed back to Earth just 3 months after launch, before the United States even launched its first successful satellite: Explorer 1. Moreover, the reason this happened wasn’t due to any technical flaw or malfunction, but due to the simple physical fact that Earth’s atmosphere doesn’t end where we erroneously and arbitrarily define the “edge of space” to be. Instead, atmospheric drag affects all satellites in low-Earth orbit, and will eventually take down everything from the International Space Station to the Hubble Space Telescope.
This Is How Hubble Will Use Its Remaining Gyroscopes To Maneuver In Space
“It might seem to be just another example of crumbling infrastructure in the United States, but you must neither underestimate Hubble nor the resourcefulness of astronomers and scientists and engineers overall. The two (or maybe three) remaining gyroscopes are of a new and upgraded design, designed to last five times as long as the original gyroscopes, which includes the one that recently failed. The James Webb Space Telescope, despite being billed as Hubble’s successor, is actually quite different, and will launch in 2021.
Even with one gyroscope, the Hubble Space Telescope should still be operational and capable of providing complementary observations to James Webb. This reduced-gyro mode has been planned for a long time. The only disappointment is that we may need to enter it so soon.”
One of the hallmarks of a successful NASA project is overengineering. Things will go wrong, break down, and degrade over time. One of the best examples is the Opportunity rover, which was designed for a 90 day mission and wound up living for nearly 15 years. But many people don’t appreciate how successfully overengineered Hubble is. Now well into its 28th year, it’s some 9 years removed from its final servicing mission. The gyroscopes that were installed included three of the old type and three of the new type, and the final old-style gyroscope has just failed.
The Most Important X-Ray Image Ever Taken Proved The Existence Of Dark Matter
“Yet the most important X-ray image of all time was an incredible surprise. This is the Bullet Cluster: a system of two galaxy clusters colliding at high speeds. As the gaseous matter inside collides, it slows, heats up, and lags behind, emitting X-rays. However, we can use gravitational lensing to learn where the mass is located in this system. he bending and shearing of light from background galaxies shows it’s separated from the matter’s and X-rays’ location. This separation is some of our strongest evidence for dark matter.”
There are many different lines of evidence for dark matter, but one of the biggest contentions of those who disbelieve it is that a direct empirical proof of its existence is needed. If it exists in a large, diffuse halo around every galaxy, cluster, and component of large-scale structure in the Universe, you should be able to prove it. Starting more than 10 years ago, astronomers have been able to do just that. When galaxy clusters collide, the overwhelming majority of normal matter, residing in the intracluster medium, should smash together, heat up, and emit X-rays. It does! But the biggest deal is that the gravitational mass, reconstructed through lensing, doesn’t coincide with the normal matter.
Its light arrives from 407 million years after the Big Bang: 3% of the Universe’s current age.”
No astronomical observatory has revolutionized our view of the Universe quite like NASA’s Hubble Space Telescope. With the various servicing missions and instrument upgrades that have taken place over its lifetime, Hubble has pushed back the cosmic frontier of the first stars and galaxies to limits never before known. Yet there must be galaxies before them; some of the most distant Hubble galaxies have stars in them that push back the time of the first galaxies to just 250 million years after the Big Bang. Yet Hubble is physically incapable of seeing that far. Three factors: cosmic redshift, warm temperatures, and light-blocking gas, prevent us from going much beyond what we’ve already seen. In fact, we’re remarkably lucky to have gotten as distant as we have.