Tag: astronomy

New sky survey uncovers hundreds of thousands of previously unknown galaxies

11:02 am

Galaxies without end: A new radio telescope sky survey has discovered hundreds of thousands of previously unknown galaxies.

This discovery is part of a major release of papers outlining a number of discoveries made by this new sky survey.

I could of course also subheaded this post “The uncertainty of science.” Wanna bet that even with this discovery we have only seen the tip of the iceberg of the number of galaxies out there?

7 comments

A very old white dwarf star with rings?

10:19 am

The uncertainty of science: A citizen scientist has discovered a very old white dwarf star that apparently has one or more dust rings it should not have.

The star, LSPM J0207+3331 or J0207 for short, is forcing researchers to reconsider models of planetary systems and could help us learn about the distant future of our solar system. “This white dwarf is so old that whatever process is feeding material into its rings must operate on billion-year timescales,” said John Debes, an astronomer at the Space Telescope Science Institute in Baltimore. “Most of the models scientists have created to explain rings around white dwarfs only work well up to around 100 million years, so this star is really challenging our assumptions of how planetary systems evolve.”

In other words, we don’t really yet understand the processes that form solar systems or even stars. This isn’t because we can’t figure this out, but because we don’t yet have enough information on hand. What we do know tells us that stars and solar systems both form from accretion disks. The information also gives us a general idea of the pattern of formation, but not much more.

For example, one question I have asked a number of astronomers is: Why are some stars gigantic monsters and others dwarfs? Based on present theories of stellar evolution, it seems to me that all stars should be the same size, as accretion is thought to end when the star reaches a heavy enough mass to ignite its nuclear engine. Yet this is not what we find. Why? I’ve never gotten a good answer.

9 comments

IAU approves China’s proposed names for Chang’e-4 landing site

10:07 am

That was fast! The International Astronomical Union (IAU) has approved all of the proposed names that China submitted for the features at or near Chang’e-4 landing site.

The IAU Working Group for Planetary System Nomenclature has approved the name Statio Tianhe for the landing site where the Chinese spacecraft Chang’e-4 touched down on 3 January this year, in the first-ever landing on the far side of the Moon. The name Tianhe originates from the ancient Chinese name for the Milky Way, which was the sky river that separated Niulang and Zhinyu in the folk tale “The Cowherd and the Weaver Girl”.

Four other names for features near the landing site have also been approved. In keeping with the theme of the above-mentioned folk tale, three small craters that form a triangle around the landing site have been named Zhinyu, Hegu, and Tianjin, which correspond to characters in the tale. They are also names of ancient Chinese constellations from the time of the Han dynasty. The fifth approved name is Mons Tai, assigned to the central peak of the crater Von Kármán, in which the landing occurred. Mons Tai is named for Mount Tai, a mountain in Shandong, China, and is about 46 km to the northwest of the Chang’e-4 landing site.

Compare this fast action with the IAU’s approval process for the names the New Horizons team picked for both Pluto and Ultima Thule. It took the IAU more than two years to approve the Pluto names, and almost three years to approve the Charon names. It is now almost two months after New Horizons’ fly-by of Ultima Thule, and the IAU has not yet approved the team’s picks for that body.

Yet it is able to get China’s picks approved in less than a month? Though it is obviously possible that there is a simple and innocent explanation for the differences here, I think this illustrates well the biases of the IAU. Its membership does not like the United States, and works to stymie our achievements if it can. This factor played a part in the Pluto/planet fiasco. It played a part in its decision to rename Hubble’s Law. And according to my sources, it was part of the background negotiations in the naming of some lunar craters last year to honor the Apollo 8 astronauts.

The bottom line remains: The IAU has continually tried to expand its naming authority, when all it was originally asked to do was to coordinate the naming of distant astronomical objects. Now it claims it has the right to approve the naming of every boulder and rock anywhere in the universe. At some point the actual explorers are going to have to tell this organization to go jump in a lake.

1 comment

Asteroid to eclipse Sirius, the sky’s brightest star, on February 18

8:46 am

On February 18, 2019 a four-mile wide asteroid is going to pass in front of Sirius, the sky’s brightest star, and block its light for just under two seconds.

Can a 7-kilometer-wide asteroid make Sirius disappear? You bet it can. That just might happen on Monday night, February 18th. That evening around 10:30 p.m. MST (5:30 UT February 19th), there’s a good probability that the 17th-magnitude 4388 Jürgenstock will occult the sky’s brightest star for up to 1.8 seconds. Visibility stretches along a narrow path from the southern tip of Baja California to the Las Cruces–El Paso region, up through the Great Plains, and north to the Winnipeg area. While only a limited number of people may see this event, anytime Sirius disappears, however briefly, it’s news!

In the U.S. the narrow path cuts through New Mexico, Colorado, Nebraska, South Dakota, and North Dakota. If you live in or near this path, this is definitely worth watching, especially since it will be happening at a convenient hour in the evening.

0 comments

Recent Cuba meteorite estimated to have weighed about 360 tons

1:36 pm

Using its imaged track from several sources, scientists have now estimated the size and weight of the recent spectacular fireball over Cuba as being several meters across and weighing about 360 tons.

After reconstructing the trajectory in the atmosphere, the Colombian astronomers “played back” the impact and found that the culprit, a rock with an estimated size of several meters and a weight of about 360 tons, came from an eccentric orbit around the Sun with an average distance to our star of 1.3 astronomical units (1 astronomical-unit = 150 million km). Before impacting the Earth, the rock completed a turn around the Sun every 1.32 years. All that came to an end on February 1, 2019 when both, the rock and the Earth, found themselves at the same point in space, at the same time. The worse part was for the rock!

The article spends most of its time selling a computer model the scientists have developed that they claim can predict the approach trajectory of meteorites, something I find quite unconvincing. However, the result above is important for different reasons. Routinely astronomers today discover new small asteroids just days before they zoom harmlessly past the Earth. Each time one of these new near Earth asteroids is found, the press automatically goes into “Chicken Little mode,” suggesting that should this object have hit the Earth it would have caused massive damage.

Most of these newly discovered asteroids are about the same size as the Cuba meteorite, if not smaller. Thus, this meteorite gives us a clear idea of how completely harmless these other near Earth asteroids are. In fact, this impact suggests to me that in most cases an asteroid would have to be about ten times larger to pose a significant threat.

Keep this number — 360 tons — in mind the next time another near Earth asteroid is discovered.

4 comments

Rare asteroid orbiting near Venus discovered

11:51 am

The Zwicky Transient Facility (ZTF), a new sky survey telescope whose main goal is to find Near Earth asteroids, has discovered a rare asteroid orbiting near Venus.

A state-of-the-art sky-surveying camera, the Zwicky Transient Facility, or ZTF, detected the asteroid on January 4, 2019. Designated 2019 AQ3, the object has the shortest “year” of any recorded asteroid, with an orbital period of just 165 days. It also appears to be an unusually big asteroidal specimen. “We have found an extraordinary object whose orbit barely strays beyond Venus’ orbit—that’s a big deal,” said Quanzhi Ye, a postdoctoral scholar at IPAC, a data and science center for astronomy at Caltech. Ye called 2019 AQ3 a “very rare species,” further noting that “there might be many more undiscovered asteroids out there like it.”

…The orbit, as it turns out, is angled vertically, taking 2019 AQ3 above and below the plane where the planets run their laps around the sun. Over its short year, 2019 AQ3 plunges inside of Mercury, then swings back up just outside of Venus’ orbit.

The telescope, in operation since March 2018, and so far found

nearly 60 new near-Earth asteroids. Two of these were spotted in July 2018 mere hours before they gave Earth quite a close shave. Designated 2018 NW and 2018 NX, the duo of bus-sized asteroids whipped past at a distance of about 70,000 miles, or only a third of the way to the moon. Fortunately, the newfound 2019 AQ3 poses no threat; the closest it ever comes to Earth is about 22 million miles.

1 comment

New Hubble images of Uranus and Neptune

9:28 am

Uranus (top) and Neptune

The Hubble Space Telescope’s new annual images of Uranus (top) and Neptune (bottom) has revealed new atmospheric features for both, a giant north pole cloud cap on Uranus and a new dark storm developing on Neptune.

For Neptune:

The new Hubble view of Neptune shows the dark storm, seen at top center. Appearing during the planet’s southern summer, the feature is the fourth and latest mysterious dark vortex captured by Hubble since 1993. Two other dark storms were discovered by the Voyager 2 spacecraft in 1989 as it flew by the remote planet. Since then, only Hubble has had the sensitivity in blue light to track these elusive features, which have appeared and faded quickly. A study led by University of California, Berkeley, undergraduate student Andrew Hsu estimated that the dark spots appear every four to six years at different latitudes and disappear after about two years.

Hubble uncovered the latest storm in September 2018 in Neptune’s northern hemisphere. The feature is roughly 6,800 miles across.

For Uranus:

The snapshot of Uranus, like the image of Neptune, reveals a dominant feature: a vast bright cloud cap across the north pole.

Scientists believe this feature is a result of Uranus’ unique rotation. Unlike every other planet in the solar system, Uranus is tipped over almost onto its side. Because of this extreme tilt, during the planet’s summer the Sun shines almost directly onto the north pole and never sets. Uranus is now approaching the middle of its summer season, and the polar-cap region is becoming more prominent. This polar hood may have formed by seasonal changes in atmospheric flow.

The images are part of an annual program that monitors both planets with images every year when the Earth is best placed to view them. This allows scientists to track atmospheric changes over time.

The sharpness of both images matches that of previous Hubble images, so these photographs do not show any decline in the telescope’s image capability. However, when they lose that next gyroscope and shift to one gyroscope mode, I believe it will be very difficult to get images even this sharp of the outer planets. In fact, I suspect this monitoring program will likely have to end, or will be badly crippled.

1 comment

The Milky Way is warped?

8:39 am

The uncertainty of science: Distance data of more than 1,300 Cepheid variable stars gathered by the Wide-field Infrared Explorer (WISE) space telescope now suggests to astronomers that the disk of the Milky Way galaxy is warped.

Trying to determine the real shape of our galaxy is like standing in a Sydney garden and trying to determine the shape of Australia. But, for the past 50 years there have been indications that the hydrogen clouds in the Milky Way are warped. The new map shows that the warped Milky Way disc also contains young stars. It confirms that the warped spiral pattern is caused by torque from the spinning of the Milky Way’s massive inner disc of stars.

This research is good and helpful in getting us closer to a real picture of our Milky Way galaxy. However, need I say that this result carries with it a great deal of uncertainty? Or should I let my kind readers outline for me the many aspects of this research that leave me with doubts?

I think I want to do the latter. Where do you think the uncertainties are in this research? What assumptions are they making? Where is their data sparse or weak? Feel free to list them in the comments.

5 comments

China’s unsupervised radio antenna in Argentina

12:01 pm

A Chinese invasion? A Chinese radio antenna in Argentina, initially proposed as a communications facility for use with China’s space program, operates without any supervision by the Argentinian government and appears to have military links.

Though U.S. government officials are pushing the idea that this facility is being used by China to eavesdrop on foreign satellites, and though China’s space program is without doubt a major arm of its military, I doubt the radio antenna is being put to military use. As the story notes

Tony Beasley, director of the U.S. National Radio Astronomy Observatory, said the station could, in theory, “listen” to other governments’ satellites, potentially picking up sensitive data. But that kind of listening could be done with far less sophisticated equipment. “Anyone can do that. I can do that with a dish in my back yard, basically,” Beasley said. “I don’t know that there’s anything particularly sinister or troubling about any part of China’s space radio network in Argentina.”

It was installed to support China’s effort to send spacecraft to the Moon and Mars, and that is likely its main purpose. China does not wish to be dependent on the U.S.’s Deep Space Network for such interplanetary communications. This facility helps make that independence possible.

At the same time, the fact that China has been allowed to establish a remote facility in another country and operate it with no oversight is definitely an issue of concern. Essentially, China has obtained control over a piece of Argentinian territory, and unless the Argentine government takes action, China can do whatever it wants there. While the antenna itself might not be an issue, the facility itself is.

0 comments

The unfinished search for the Hubble constant

10:40 am

The uncertainty of science: Scientists continue to struggle in their still unfinished search for determining the precise expansion rate for the universe, dubbed the Hubble constant in honor of Edwin Hubble, who discovered that expansion.

The problem is, the values obtained from [two different] methods do not agree—a discrepancy cosmologists call “tension.” Calculations from redshift place the figure at about 73 (in units of kilometers per second per megaparsec); the CMB estimates are closer to 68. Most researchers first thought this divergence could be due to errors in measurements (known among astrophysicists as “systematics”). But despite years of investigation, scientists can find no source of error large enough to explain the gap.

I am especially amused by these numbers. Back in 1995 NASA had a big touted press conference to announce that new data from the Hubble Space Telescope had finally determined the exact number for the Hubble constant, 80 (using the standard above). The press went hog wild over this now “certain” conclusion, even though other astronomers disputed it, and offered lower numbers ranging from 30 to 65. Astronomer Allan Sandage of the Carnegie Observatories was especially critical of NASA’s certainty, and was dully ignored by most of the press.

In writing my own article about this result, I was especially struck during my phone interview with Wendy Friedman, the lead scientist for Hubble’s results, by her own certainty. When I noted that her data was very slim, the measurements of only a few stars from one galaxy, she poo-pooed this point. Her result had settled the question!

I didn’t buy her certainty then, and in my article, for The Sciences and entitled most appropriately “The Hubble Inconstant”, made it a point to note Sandage’s doubts. In the end it turns out that Sandage’s proposed number then of between 53 and 65 was a better prediction.

Still, the science for the final number remains unsettled, with two methods coming up with numbers that are a little less than a ten percent different, and no clear explanation for that difference. Isn’t science wonderful?

1 comment

Moon hit by small meteorite during eclipse

12:57 pm

During the lunar eclipse two days ago on January 20, 2018 amateur astronomers were able to record the impact of a small meteorite.

The MIDAS survey is a Moon-watching that scours video of its surface in the hopes of detecting the tiny flashes associated with meteorite impacts. In this case, MIDAS scored a home run, and it was the first time the system was able to spot an impact during a total lunar eclipse.

“In total I spent almost two days without sleeping, including the monitoring time during the eclipse,” [Jose] Madiedo explained to Gizmodo. “I was exhausted when the eclipse ended—but when the automatic detection software notified me of a bright flash, I jumped out of my chair. It was a very exciting moment because I knew such a thing had never been recorded before.”

The meteorite itself wasn’t terribly large, and is estimated to have only been around 22 pounds.

I have embedded the video of the impact below the fold. It is very short, and the flash is not very impressive, but it still is quite cool.
» Read more

3 comments

Is the pole of the Milky Way’s central black hole pointing directly at us?

9:42 am

The uncertainty of science: New data obtained using a constellation of Earth-based telescopes, working as a unit, strongly suggests that the pole of the Milky Way7s supermassive central black hole, dubbed Sagittarius A* (pronounced A-star), is pointing directly at us.

The high quality of the unscattered image has allowed the team to constrain theoretical models for the gas around Sgr A*. The bulk of the radio emission is coming from a mere 300 milllionth of a degree, and the source has a symmetrical morphology. “This may indicate that the radio emission is produced in a disk of infalling gas rather than by a radio jet,” explains Sara Issaoun, graduate student at the Radboud University Nijmegen in the Netherlands, who leads the work and has tested several computer models against the data. “However, that would make Sgr A* an exception compared to other radio emitting black holes. The alternative could be that the radio jet is pointing almost at us”.

The German astronomer Heino Falcke, Professor of Radio Astronomy at Radboud University and PhD supervisor of Issaoun, calls this statement very unusual, but he also no longer rules it out. Last year, Falcke would have considered this a contrived model, but recently the GRAVITY team came to a similar conclusion using ESO’s Very Large Telescope Interferometer of optical telescopes and an independent technique. “Maybe this is true after all”, concludes Falcke, “and we are looking at this beast from a very special vantage point.”

If this is true, it might explain why Sgr A* is generally observed to be one of the quietest central supermassive black holes known. Compared to many others, its flux of emissions is far less.

1 comment
1 … 79 80 81 82 83 … 188