Wednesday, November 14, 2018
Andrew Fraknoi: Exploring the Universe: A Possible New Planet Around the Second Closest St...: A Possible New Planet Around the Second Closest Star System to Earth An international team of astronomers is announcing the possible d...
A Possible New Planet Around the Second Closest Star System to Earth
An international team of astronomers is announcing the possible discovery of a planet around the second closest star system to us, Barnard’s Star. A mere 6 light-years away, the star is a faint red dwarf which gives off only four hundredths of a percent of the Sun’s light energy. The planet, which could be as massive as 3 Earths, is orbiting at the same distance as Mercury is from the Sun, but is still colder than Saturn and unlikely to harbor life as we know it.
Since the closest star system to us also has a known planet in it, this discovery (if it is confirmed) would make it even more likely that planets are “more common than dirt” out there. Four planetary systems would then be known among the stars 10 light-years or closer. Some 2900 planetary systems (containing almost 4,000 planets) have now been found in our galactic neighborhood.
The new planet, which takes 233 days to orbit, was detected from the very slight “wiggles” that the planet’s gravity (as it goes around) gives to the motion of its star. The wiggles are so small that it took 20 years of observations, using special equipment on various telescopes around the world, to identify them. While it’s still possible that their combined observations have another explanation, the 63 authors on the paper announcing the planet have dug deeply into their data statistics and claim that the planet idea is the most likely explanation. Not all experts in the field agree that this is a definite detection. Instruments of the future, with better ability to detect tiny star wiggles, will ultimately decide if the planet is real.
Our image shows an artist conception of what the the “cold, hostile desert” surface of the planet around Barnard’s Star, with a temperature of -270 degrees Centigrade, might look like. (You will need to take your parka if you go.)
Thursday, August 9, 2018
This Sunday evening and Monday morning, there will be one of the best meteor showers you and your family can watch – the Perseids. And since the Moon will not be in the sky during this shower, dark skies will make it easier for even casual viewers to spot a good number of “shooting stars.”
The best night is the evening of Aug. 12th and morning of Aug. 13th, although there could be significantly more meteors in the sky on the night before and the night after too. Meteors or “shooting stars” (which have nothing to do with stars) are pieces of cosmic dust and dirt hitting the Earth’s atmosphere at high speed and making a flash of light. These flashes could happen anywhere in the sky, so it’s best to view the shower from a dark, wide-open place. See the list at the end for viewing suggestions.
The Perseid meteors are cosmic “garbage” left over from a regularly returning comet, called Swift-Tuttle (after the two astronomers who first discovered it). The comet itself returns to the inner solar system every 130 years or so; it was last here in 1992. During each pass, it leaves dirt and dust behind and it is this long dirt and dust stream that we encounter every August.
Each flash you see is a bit of material from the comet hitting the Earth’s atmosphere and getting heated up (and heating up the air around it) as it speeds through our thick atmosphere. Both the superheated dust and dirt and the heated air contribute to the visible light we observe. Since comets are left-overs from the early days of our solar system, you can tell yourself (or your kids) that each flash of light is the “last gasp” of a bit of cosmic material that formed some 5 billion years ago.
MY EIGHT HINTS
FOR “TAKING A METEOR SHOWER”
1. Get away from city lights and find a location that’s relatively dark
2. If it’s significantly foggy or cloudy, you’re out of luck
3. Your location should allow you to see as much of the dome of the sky as possible
4. Allow time for your eyes to get adapted to the dark (at least 10 -15 minutes)
5. Don’t use a telescope or binoculars – they restrict your view (so you don’t have to be part of the 1% with fancy equipment to see the shower; this is a show for the 99%!)
6. Dress warm – it can get cooler at night even in August (and don’t forget the insect repellent while you are outside)
7. Be patient (it’s not fireworks): keep looking up & around & you’ll see flashes of light
8. Take someone with you with whom you like to spend time in the dark!
[The photo shows a Perseid meteor over the Very Large Telescope at the European Southern Observatory in Chile.]
Sunday, February 4, 2018
With veteran talk-show host and ABC-radio newscaster Gil Gross, we are starting a new series of podcasts to be called “Fraknoi’s Universe.” (It helps to have an unusual last name!)
The pilot episode (made last summer about the total eclipse of the Sun): https://districtproductive.com/fraknois-universe/ was a success on a number of CBS radio stations, and on the Web. So we are starting to record further episodes, discussing the latest news and discoveries from the worlds of astronomy and space exploration.
As part of the program, we’d like to answer general astronomyquestions from interested members of the public. If you have a question (focused on astronomy and space) that you’d like to ask, please e-mail me at:
Be sure you include your full name and home town, so we can mention it on the air.
Feel free to pass this on to others interested in astronomy.
When the shows are ready, we’ll announce them here and on other social media.
Thanks very much.
Thursday, January 25, 2018
On Wednesday morning, January 31, residents of North America (and particularly those on the west coast) will experience a rare triple event:
* The full moon will enter the Earth’s shadow and show a total eclipse (turning the full moon into a dark reddish disk)
* This will be the second full moon in the same month – something we call a blue moon
* And it will be a “supermoon,” where the Moon is full just as it’s closest to our planet Earth (this last thing by itself is not especially rare; in fact it will be third “supermoon” in a row).
Having all three together is unusual. The last time we had a blue moon totally eclipsed in the U.S. was more than 150 years ago.
Here are the times of the eclipse of the Moon on the morning of January 31 in different U.S. time zones:
Eclipse Circumstance Pacific Mountain Central Eastern
Partial eclipse begins 3:48 am 4:48 am 5:48 am 6:48 am
Total eclipse begins 4:52 am 5:52 am 6:52 am ---
Total eclipse ends 6:08 am 7:08 am --- ---
Partial eclipse ends 7:11 am --- --- ---
Total eclipse begins 4:52 am 5:52 am 6:52 am ---
Total eclipse ends 6:08 am 7:08 am --- ---
Partial eclipse ends 7:11 am --- --- ---
--- means that Moon has already set (is below the horizon)
You can see that in the eastern half of the U.S., the full Moon sets before the total eclipse or just as the eclipse is getting good, but in the western half of the U.S., some or all of the eclipse will be ready to delight those who can get up early (before the Sun does) that morning.
If you are planning to get up to see the last part of the total eclipse, there is one other factor to keep in mind. The eclipsed Moon is setting in the west as the Sun is rising in the east. That means you have to have a clear sight-line toward the western horizon for the eclipse. If buildings or trees block your view in that direction, you could miss the event. So scout out the location where you plan to be in advance. (Maps and charts can be seen at: http://www.skyandtelescope.com/obser…/january-lunar-eclipse/ )
Note: Only the total eclipse turns the Moon an eerie dark red (because of the bending of red light in the Earth’s atmosphere.) Once the total eclipse is over, the reddish effect that eclipse fans like (and the media call a "blood moon") will be gone.
Our remarkable photo, by Elias Politis, shows a 2011 lunar eclipse sequence over the Acropolis in Greece. Click on the image to see it larger.
Saturday, December 30, 2017
By a cosmic coincidence, the first day of 2018 will have a nice full Moon in the evening. And the full Moon occurs just when the Moon is closest to the Earth in its monthly orbit, so it will look a little bigger to us in the sky.
Since 2011, the media have followed a suggestion by an astrologer (!) and started calling these slightly closer full Moons "Supermoons" -- a name more likely to make people notice. We astronomers tried to fight the term, but we're mostly giving up.
On January 1, the Moon will be closest (at perigee) at 2 pm, Pacific time: it will be 221,600 miles from us. (The average distance is about 239,000 miles.) The full Moon officially happens only 4 hours or so later, at around 6 pm Pacific time.
So when the full Moon rises, in the evening, as the Sun sets, it will looks somewhat bigger and brighter than usual. It's no big deal, except to reporters eager to fill news copy during the holidays when news is slow. Still, it's always nice to have an excuse to notice the full Moon and show it to kids in your family or neighborhood.
Remember, the Moon is the only world other than Earth on which humans (12 of them) have stood and explored. Even just with your naked eye (but better with a pair of binoculars), you can see some of the bigger round craters on the Moon, evidence of the ancient violence that was common in the early days of the solar system. More than four billion years ago, large chunks of rock and ice were still moving around the system, hitting the forming planets and moons.
January 2018 is a blue-moon month (meaning two full moons will happen in the same month) and the second full moon, on January 31, will be more impressive. It will include not only a Supermoon, but a total eclipse of the Moon!
That eclipse will be best on the West Coast, but it will happen early in the morning. So you'll have to get up at 5:30 or 6 am on a Wednesday morning to see the full Moon fully eclipsed. I will have a much more detailed preview of the eclipse in this column when it's a closer in time.
Our photo, by astro-photographer Rick Baldridge, shows a full Moon seen above the historic Lick Observatory near San Jose. Click on it to see it bigger.
On a personal note, I have just launched my own astronomy website at http://www.fraknoi.com and invite you to check it out. It's still a work in progress.
Tuesday, November 28, 2017
Astronomers around the world have been observing a small but fast object that gives every indication of coming from some other star system. It's the first such "interstellar" visitor we have ever observed. And it's characteristics are quite unexpected.
Most astronomers expected the first such deep-space visitor to be a comet -- a chunk of icy material (which our solar system has in great abundance outside the orbits of the main planets.) But all the characteristics of this visitor argue against that idea. It didn't evaporate and develop a "tail" as it came closer to the Sun than Mercury. Any comet would have done that.
And it seems to spin in less than 8 hours. Something made of snowballs or ice might fall apart from such a fast spin. So it appears that our visitor is made of rock -- more like an asteroid and not like a comet. And its color is dark and reddish, like some asteroids we have seen from our own system.
Furthermore, its shape -- which we can estimate from the way the sunlight reflected from it changes -- is also odd. It appears to be much longer than it is wide. Our best estimate is a cigar shape (see the attached painting from the European Southern Observatory), perhaps half a mile long and only 80 yards in diameter. But it could also be a flat cylinder -- which reminds some people of the shape of the main body of the Starship Enterprise.
(Just to be sure, astronomers at the SETI Institute used their antenna array in Northern California to check if the visitor was sending any radio messages. Nothing was found.)
First discovered by a team led by Karen Meech of the University of Hawaii using a Hawaiian telescope, the visitor has been given a Hawaiian name: Oumuamua, which means "scout or messenger, arriving first" -- not a bad fit. Its scientific designation is 1I2017U1. The 1I stands for first interstellar object ever discovered!
When we found it on Oct. 19th, it was coming in fast from the direction of the constellation of Lyra. It's now going out at a speed of 86,000 mph relative to the Sun. It already crossed the orbit of Mars and will reach the distance of Jupiter in May 2018. Having been whipped around by the Sun's gravity, it will go out in a new and random direction, back toward the realm of the stars.
We expect that such visitors should be passing through all the time, but we haven't discovered them until now. With new surveys of small, dim objects in the sky soon getting under way, we expect to find a lot more small pieces from our own neighborhood -- and beyond. Stay tuned.