I love rocks. I love astronomy. Happy days!
From a post I put in my online astronomy class:
Do you like learning astronomy and, at least in your mind, exploring the universe and learning what's really out there? You are not alone. That is one of the reasons why your taxpayer dollars, and other countries, too, fund space exploration and research programs.
Right now we are accomplishing a lot of exciting space exploration.
NASA (the United States' National Aeronautics and Space Administration) has put a satellite into orbit around an asteroid, a sort of small-medium-sized asteroid named Bennu.
Bennu is an Apollo asteroid, one that orbits nearer to the Sun than the asteroid belt out past Mars where most asteroids hang out, nearer to the Sun than Mars. In fact, Bennu's orbit crosses Earth's orbit, occasionally. There is a small chance that at some point in the future, Bennu will collide with Earth. Bennu has an average diameter of about 480 m, or 1,600 ft.
This is where I got the video composite of Bennu from: NASA's OSIRIS-REx Arrives at Asteroid Bennu, Sends Awesome New Imagery
Also in the news, the New Horizons satellite, another NASA probe, just passed by - on New Year's Day, as it happens - an object that is neither an asteroid nor a planet, and looks kind of like two potatoes stuck together.
It is called Ultima Thule, although whether that will stay its name for the long term is currently not determined.
Its official name is 2014 MU69, it is catalogued as minor planet number 485968, and it is called a dwarf planet in some descriptions, causing us to consider what that means (see "Why I Killed Pluto and Why it Had It Coming" by Mike Brown).
Looking at Ultima Thule, you can see that it is not large enough to have gravity strong enough to force its material into a spherical shape. Its lack of a spherical shape would seem to disqualify it from the dwarf planet category.
The image above of MU69, "Ultima Thule," is copied from CNN, which calls it a "space snowman." The New Horizons satellite gathered the image data from thousands of miles away, which means it can only be so detailed. The blurry image was measuring color wavelengths, the black and white image is for surface details, and the image on the right is a computerized combination of color and shape.
So what is Ultima Thule? Ultima Thule is a Kuiper belt object, or KBO, the same group of Solar System objects that dwarf planet Pluto is a member of. Ultima Thule is a lot farther out from the Sun than Pluto is, and is thought to be roughly in the middle of the Kuiper belt.
Ultima Thule is probably made of rock, carbon, and ice, and not just water ice, also frozen methane and other volatile substances. Ultima Thule is in the deep freeze of outer space, too far from the Sun to get any warmth from it. Interestingly, there are probably organic molecules on Ultima Thule's surface. As more data measured by New Horizons comes in, we will learn more about the stuff that Ultimate Thule is made of.
Ultima Thule was estimated from a distance to be about 9 miles wide by 21 miles long, numbers that were determined before New Horizons passed by. Those numbers don't tell us the details of its shape.
Based on this new imagery, Ultima Thule is now thought to be two Kuiper belt objects that collided relatively gently and just barely stuck together, creating a "contact binary" object. The larger piece of the binary is 12 miles across and the smaller piece is 9 miles across.
This double-lobed, contact binary, if that's what is is, appears to be an unusual form of solar system object, based on our limited explorations in the Solar System. But we've hardly looked at any Kuiper Belt objects up close before, so perhaps it not so unusual, out there in the icy distant reaches of the Solar System, for a couple of KBOs to somehow coalesce into pair of bodies that are touching each other, or orbiting each other in extremely close proximity, without colliding disruptively and without fully merging with each other. Exactly how this would happen, and whether it is common, is yet to be worked out.
According to the Google dictionary, Ultima Thule means "a distant unknown region; the extreme limit of travel and discovery." It is the farthest object from Earth that we have ever visited.
Ultima Thule is approximately 44 AU away, or 44 times the distance from the Sun to the Earth. That's about four billion miles, or 4,000,000,000 mi. In kilometers, it's 6,600,000,000 km.
The New Horizons satellite has already fulfilled its primary mission of passing by, imaging, and measuring Pluto and Pluto's five moons, but the satellite is still operating.
We, or rather our rocket scientist friends at NASA (as in the picture below, of the team at the New Horizons control center), intentionally put New Horizons on a path that would take it near Ultima Thule, to find out more about this very distant, very miniature planet. (OK, it does not qualify, strictly speaking, as a true planet. I meant it colloquially.)
New Horizons was launched in early 2006. It takes awhile to travel four billion miles.
The adjustment to New Horizon's path to send it toward Ultima Thule was made after the satellite had passed by Pluto in 2015. MU69 had been discovered by the Hubble Space Telescope in 2014, on a search for possible targets beyond Pluto. The New Horizons team chose it as the next target from a list of several possibilities, all of which were tiny points of light in the Hubble images. So in November of 2015 they sent the signal to have New Horizons fire its thrusters appropriately, and on its way it went to the strange object, or pair of objects, that we now call Ultima Thule.
It is amazing how sustainable and adaptable the design of New Horizons has proved to be, and its digital technology is from decades ago, prior to touch-screen smartphones. Way to go, you scientists and engineers!
Today and in the coming days, there will be more images and data gathered by the New Horizons satellite, and released by NASA, to give us a more detailed view of Ultima Thule. In fact, it is expected to take over a year for all the gigabytes of data on Ultima Thule to get transmitted back to Earth.
As I write this, New Horizons is on the opposite side of the Sun from Earth, shutting off radio communication for several days before more data can start coming back to Earth again.
The slightly blurry pair of potatoes, the snowman, is just the first glimpse.
Once all the data has been received, there are likely to be much closer-in, more detailed images of Ultima Thule along with other measurements to tell us more about us what it is and how it formed.
I don't expect Ultima Thule to be the farthest-out object we will send a satellite to and discover more about in my lifetime. There is a chance that the New Horizons satellite may itself encounter a further-out KBO on its continued journey. What about you, do you expect that we will explore objects farther away than Ultima Thule?
So there you go: NASA has just put a satellite in orbit around the smallest object we've ever got a satellite to orbit in the gravity hold of, the near-Earth asteroid Bennu.
And NASA just got a satellite to pass by and gather data on the most distant object, by far, that we've ever sent a satellite to, the Kuiper belt object "Ultima Thule," way out past Pluto.
Both satellites will be sending in a lot more data in coming weeks and months, and ultimately, the satellite sent to asteroid Bennu is supposed to collect a sample and send it back to Earth for us to analyze. That will take a few years, until 2023.
I should mention that China just put a lunar lander on the far side of the Moon, the first time that has been done. No, not the dark side, the far side. The Sun shines on all sides of the Moon over the course of each monthly pirouette. Get it straight, news media. Geez.
For 2024, I hope to go see the total eclipse of the Sun, perhaps with relatives my wife and I have in Texas. You should see it, too. The point is, astronomy is all around us. The experts are learning an incredible amount of detail. It's fun to share in their explorations and learn along with them. Just learning a little bit, and experiencing some of the amazing sights of the worlds beyond Earth, is wonderful.
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