That was close

Didn’t think it would end like this

I’m certainly no fan of media scare-mongering, but I feel like this should have been a bigger story than it was – after all, the Smithsonian Astrophysical Observatory’s Minor Planet Center classified the asteroid as a “potentially hazardous object”:

Asteroid 1999 KW4, measuring more than a mile in diameter and boasting its own moon, will fly by Earth on Saturday. Thankfully, the massive space rock will make its pass at a safe distance.

“The asteroid will approach from the south, and the first day of visibility also coincides with the closest approach,” NASA reported.

The asteroid will be visible through June 7.

While the near-Earth object is classified as a potentially hazardous asteroid, there will be a cushy 3.2 million miles between Earth and the walnut-shaped space rock during its closest approach.

That distance, I would note, is roughly 1/29 of the sun’s distance from the earth.

Wouldn’t want the sheeple to panic! In any case, it’s Sunday so I guess the asteroid has safely completed its fly-by?

The weight of the Milky Way

It’s heavy:

Measuring the total mass of our home galaxy is a tough puzzle. It’s difficult to see it all at once, buried as we are within one of its spiral arms. And there’s a huge portion of the Milky Way we can never see, since it’s made up of dark matter, which doesn’t emit light at all. So to get an accurate number, researchers need to weigh both the visible and invisible material that makes up the galaxy.

Now scientists have done just that, using new data from the Hubble Space Telescope combined with the Gaia spacecraft. This latest mass measurement of the Milky Way weighs in at 1.5 trillion times heavier than our sun.

Now, how heavy is the universe? Assuming the Milky Way is an average galaxy, and there are 200 billion galaxies in the universe, then all galaxies combined would weigh 300 sextillion (300,000,000,000,000,000,000,000) times the mass of the sun, and that’s not counting all the stuff drifting around between galaxies.

About that weird interstellar object

This is a nice interview with a prominent Harvard space scientist regarding the mysterious elongated object that was observed hurtling through the solar system in 2017, marking our first close brush with an interstellar entity:

On October 19, 2017, astronomers at the University of Hawaii spotted a strange object travelling through our solar system, which they later described as “a red and extremely elongated asteroid.” It was the first interstellar object to be detected within our solar system; the scientists named it ‘Oumuamua, the Hawaiian word for a scout or messenger. The following October, Avi Loeb, the chair of Harvard’s astronomy department, co-wrote a paper (with a Harvard postdoctoral fellow, Shmuel Bialy) that examined ‘Oumuamua’s “peculiar acceleration” and suggested that the object “may be a fully operational probe sent intentionally to Earth’s vicinity by an alien civilization.” Loeb has long been interested in the search for extraterrestrial life, and he recently made further headlines by suggesting that we might communicate with the civilization that sent the probe. “If these beings are peaceful, we could learn a lot from them,” he told Der Spiegel.

Quote from Loeb:

Well, it’s exactly the approach that I took. I approached this with a scientific mind, like I approach any other problem in astronomy or science that I work on. The point is that we follow the evidence, and the evidence in this particular case is that there are six peculiar facts. And one of these facts is that it deviated from an orbit shaped by gravity while not showing any of the telltale signs of cometary outgassing activity. So we don’t see the gas around it, we don’t see the cometary tail. It has an extreme shape that we have never seen before in either asteroids or comets. We know that we couldn’t detect any heat from it and that it’s much more shiny, by a factor of ten, than a typical asteroid or comet. All of these are facts. I am following the facts. […]

But when you mention the possibility that there could be equipment out there that is coming from another civilization—which, to my mind, is much less speculative, because we have already sent things into space—then that is regarded as unscientific. But we didn’t just invent this thing out of thin air. The reason we were driven to put in that sentence was because of the evidence, because of the facts.

As Sherlock Holmes said: “When you have excluded the impossible, whatever remains, however improbable, must be the truth.”

More here and here.

UPDATE: From the Haaretz article, I found this interesting:

What does it feel like to sit next to colleagues in a university lunchroom a day after publishing an article arguing that Oumuamua may actually be a reconnaissance spaceship?

Loeb: “The article I published was written, in part, on the basis of conversations I had with colleagues whom I respect scientifically. Scientists of senior status said themselves that this object was peculiar but were apprehensive about making their thoughts public. I don’t understand that. After all, academic tenure is intended to give scientists the freedom to take risks without having to worry about their jobs. Unfortunately, most scientists achieve tenure – and go on tending to their image. As children we ask ourselves about the world, we allow ourselves to err. Ego doesn’t play a part. We learn about the world with innocence and honesty. As a scientist, you’re supposed to enjoy the privilege of being able to continue your childhood. Not to worry about the ego, but about uncovering the truth. Especially after you get tenure.”

Here’s more about the Loeb Hypothesis:

If it wasn’t comet outgassing, what force caused Oumuamua to accelerate? It is precisely here where Loeb enters the picture. According to his calculations, Oumuamua’s acceleration was caused by a push.

“The only hypothesis I could think of,” he relates, “is a push from solar radiation pressure. For that to work, the object would have to be very thin, less than a millimeter thick, in other words a type of pancake. In addition, the Spitzer Space Telescope found no evidence of heat emission from the object, and that means that it is at least 10 times more reflective than a typical comet or asteroid. What we have, then, is a thin, flat, shiny object. So I arrived at the idea of a solar sail: A solar sail is a spaceship that uses the sun for propulsion. Instead of using fuel, it is propelled ahead by reflecting light. In fact, it’s a technology that our civilization is developing at this very time.”

Bottles in space

Avi Loeb definitely knows a thing or two about solar sails. In 2016, the physicist and venture capitalist Yuri Milner, together with Stephen Hawking, Mark Zuckerberg and others, established Breakthrough Starshot, an initiative to accelerate solar sails to one-fifth the speed of light in order to explore the neighboring solar system, Alpha Centauri, which is four light-years away from us. Loeb was appointed the project’s scientific director.

I wrote about Breakthrough Starshot a couple years ago here.

Contact?

I don’t know whether this is a message from aliens, but the universe is most definitely alive:

Astronomers have revealed details of mysterious signals emanating from a distant galaxy, picked up by a telescope in Canada.

The precise nature and origin of the blasts of radio waves is unknown.

Among the 13 fast radio bursts, known as FRBs, was a very unusual repeating signal, coming from the same source about 1.5 billion light years away.

Such an event has only been reported once before, by a different telescope. […]

FRBs are short, bright flashes of radio waves, which appear to be coming from almost halfway across the Universe.

Here’s a related item about the vast number of FRBs being detected by Australian scientists.

Luna incognita

Far side of moon China

A glimpse of the far side

We have a touchdown:

China successfully landed the Chang’e 4 spacecraft on the far side of the moon on Thursday morning, Beijing time, according to state news agency Xinhua, becoming the first in history to touch the lunar surface unseen by those on Earth.

The Chang’e 4 mission launched in early December. It took the spacecraft three days to travel to the moon, where it spent the last few weeks in orbit preparing for touch down on the Von Karman crater. The crater is a relatively flat spot on the moon’s far side.

“China’s Chang’e-4 probe softlands on Moon’s far side,” the state news agency tweeted on Thursday.

[…]

Landing on the far side is a technical challenge, as there is no direct way to communicate with the spacecraft as it nears its target. China put a relay satellite in orbit around the moon in May to overcome that communication challenge.

The far side of the moon has been seen and mapped before, even by astronauts of the Apollo missions. But the successful landing of Chang’e 4 represents the first time any spacecraft has touched down on the moon’s far side.

Most impressive.

Alpha Centauri Sucks

Latest XKCD cartoon:

I believe this is known as a “dad joke.” In any case, nothing wrong with a little mild astronomy humor. Astro-comedy? Reminds me of this quote from Douglas Adams’s The Restaurant at the End of the Universe:

The History of every major Galactic Civilization tends to pass through three distinct and recognizable phases, those of Survival, Inquiry and Sophistication, otherwise known as the How, Why, and Where phases. For instance, the first phase is characterized by the question ‘How can we eat?’ the second by the question ‘Why do we eat?’ and the third by the question ‘Where shall we have lunch?”

(See also. And.)

An awful lot of photons

NASA Fermi 5 years gamma

Or, to be precise, 4×10^84 (that’s 4 with 84 zeros): the total amount of photons emitted by stars in the entire universe.

Clemson University scientists, relying on imagery from NASA’s Fermi Gamma-ray Space Telescope, claim for the first time to have measured all of the starlight ever generated throughout the history of the observable universe.

By the numbers: According to the new data, which was published in the journal Science on Friday, the number of photons — particles of visible light — emitted by stars amounts to 4 times 10 to the 84th power.

Russia to verify moon landings

Buzz Aldrin moon July 1969

I always thought this looked fake

It’s time someone cleared this up once and for all:

The head of Russia’s Roscosmos space agency has said that a proposed Russian mission to the moon will be tasked with verifying that the American moon landings were real, though he appeared to be making a joke.

“We have set this objective to fly and verify whether they’ve been there or not,” said Dmitry Rogozin in a video posted Saturday on Twitter.

Rogozin was responding to a question about whether or not NASA actually landed on the moon nearly 50 years ago. He appeared to be joking, as he smirked and shrugged while answering. But conspiracies surrounding NASA’s moon missions are common in Russia.