Charlie McDonnell is a phenomenally successful YouTube blogger, with more than 2 million subscribers. And from time to time he likes to wrap his head around complicated topics in space and astronomy.
In this short video, Charlie tackles the implications of what it means to live in an infinite Universe. If the Universe is truly infinite, and there are a finite number of ways that matter can be configured, then if you travel far enough, you will run into duplicates. Continue reading “Are There an Infinite Number of Charlies?”
Scfeenshot from NASA TV of the HTV-4 launch from Japan.
More supplies and a brand new talking robot for International Space Station. The Japan Aerospace Exploration Agency’s (JAXA) HTV-4 Transfer Vehicle launched successfully from the Tanegashima Space Center in Japan, and will rendezvous in six days with the ISS. On board are 3.6 tons of dry cargo, water, experiments and spare parts to the International Space Station. The new robot, a .34 meter (13.4-inch) robot named Kirobo, is designed to be able to have a conversation with its astronaut crewmates and to study how robot-human interactions can help the astronauts in the space environment.
Unlike a Russian Progress vehicle which docks automatically, the HTV-4 will be captured by the Canadarm2 and berthed to the Harmony module. The cargo spacecraft will be commanded to fly within about 40 feet and then hold where Flight Engineer Karen Nyberg will operate the Canadarm2 during the approach and rendezvous of the Kountouri supply vehicle.
A mosaic by the Mars Science Laboratory Curiosity rover, assembled by Ken Kremer and Marco Di Lorenzo is now part of the permanent Solar System Exhibit outside the National Air and Space Museum on the US National Mall in Washington, D.C. Image courtesy Ken Kremer.
Congratulations to Universe Today writer Ken Kremer and his partner in image editing, Marco Di Lorenzo, who have had one of the panoramas they created from the Curiosity rover’s imagery included in a permanent Solar System exhibit outside the National Air and Space Museum on the US National Mall in Washington, D.C. The exhibit is called “Voyage” and was created by the National Center for Earth and Space Science Education (NCESSE) and is sponsored in part by NASA.
Ken said the NCESSE contacted him a few months ago back to use the mosaic — from Sol 169 of Curiosity’s time on Mars — and the project is finally complete. “They liked and chose it because it evokes a human presence on Mars with the rover in the foreground,” Ken said.
The exhibit is a one to 10-billion scale model of our Solar System—spanning 600 meters (6,000 feet) from the National Air and Space Museum to the Smithsonian Castle Building, and Ken and Marco’s image from the Curiosity rover is part of the information about Mars.
Here’s a description of the exhibit from NCESSE website:
“The Voyage exhibition on the National Mall, installed in 2001, was created through a partnership between Challenger Center for Space Science Education, the Smithsonian Institution, and NASA. A summer 2013 update of this exhibition’s content was undertaken by the National Center for Earth and Space Science Education and the Smithsonian Institution, through a grant from the District of Columbia Space Grant Consortium. To learn more, and view photo albums of all Voyage exhibitions, visit the Voyage National Program page.”
Here’s a closeup of Ken and Marco’s mosaic:
Close up of the Mars placard for the Voyager Solar System exhibit. Image courtesy of Ken Kremer.
And a full view of the image is below.
You can learn more about the exhibit at the NCESSE Voyage webpage. Again, congratulations to Ken and Marco!
Curiosity accomplished Historic 1st drilling into Martian rock at John Klein outcrop on Feb 8, 2013 (Sol 182), shown in this context mosaic view of the Yellowknife Bay basin taken on Jan. 26 (Sol 169). The robotic arm is pressing down on the surface at John Klein outcrop of veined hydrated minerals – dramatically back dropped with her ultimate destination; Mount Sharp. Credit: NASA/JPL-Caltech/Ken Kremer/Marco Di Lorenzo
The radiant for the Persieds, looking to the NE from latitide ~30N at around 2AM local. Created by the Author in Starry Night).
Get set for the meteoritic grand finale of summer.
Northern hemisphere summer that is. As we head into August, our gaze turns towards that “Old Faithful” of meteor showers, the Perseids. Though summer is mostly behind us now, “meteor shower season” is about to get underway in earnest.
Pronounced “Pur-SEE-ids,” this shower falls around the second week of August, just before school goes back in for most folks. This time of year also finds many the residents of the northern hemisphere out camping and away from light-polluted suburban skies.
This year also offers a special treat, as the Moon will be safely out of the sky during key observation times. The Moon reaches New phase on August 6th at 5:51 PM EDT/ 9:51 Universal Time (UT) and will be a 32% illuminated waxing crescent around the anticipated peak for the Perseid meteors on August 12th. And speaking of which, the Perseids are infamous for presenting a double-fisted twin peak in activity. This year, the first climax for the shower is predicted for around 13:00 UT on August 12th, favoring Hawaii and the North American west coast, and the second peak is set to arrive 13 hours later at 02:00 UT, favoring Europe & Africa.
Nodal crossing for the Perseid stream and Earth’s orbit sits right around 18:00 to 21:00 UT on August 12th for 2013. The shower derives its name from the constellation Perseus, and has a radiant located near Gamma Persei at right ascension 3 hours 4 minutes and a declination of +58 degrees. Atmospheric velocities for the Perseids are on the high end as meteor showers go, at 59km/sec.
Of course, like with any meteor shower, it’s worth starting to watch a few days prior to the peak date. Although meteor streams like the Perseids have been modeled and mapped over the years, there are still lots of surprises out there. Plus, starting an early vigil is insurance that you at least catch some action in the event that you’re clouded out on game day! Like we mentioned in last week’s post on the Delta Aquarids, the Perseids are already active, spanning a season from July 17th to August 24th.
The Zenithal Hourly Rate for the Perseids is generally between 60-100 meteors. The ZHR is the number of meteors you could expect to see during optimal conditions under dark skies with the radiant directly overhead. Rates were enhanced back in the 1990’s, and 2004 saw a ZHR of 200.
The orbit of comet Swift-Tuttle and its intersection near the Earth’s orbit. (Created by the author using NASA/JPL ephemerides generator).
The source of the Perseids is comet 109P/Swift-Tuttle. Discovered on July 16th-19th, 1862 by astronomers Lewis Swift & Horace Tuttle, Swift-Tuttle is on a 133.3 year orbit and last passed through the inner solar system in late 1992. This comet will once again grace our skies in early 2126 AD.
The Perseids are also sometimes referred to as the “tears of St Lawrence,” after the Catholic saint who was martyred on August 10th, 258 AD. The Perseids have been noted by Chinese astronomers as far back as 36 AD, when it was recorded that “more than 100 meteors flew thither in the morning.” The annual nature of the shower was first described by Belgian astronomer Adolphe Quételet in 1835.
Enhanced rates for the Perseids marked the return of comet Swift-Tuttle in the 1990s. Recent years have seen rates as reported by the International Meteor Organization at a ZHR=175(2009), 91(2010), 58(2011), & a resurgence of a ZHR=122 last year.
Just what will 2013 bring? There’s one truism in meteor observing—you definitely won’t see anything if you do not get out and observe. Meteor shower observing requires no equipment, just clear skies and patience. Watch in the early hours before dawn, when the rates are highest. Meteors can occasionally be seen before midnight, but are marked by lower rates and slow, stately trains across the sky. Some suggest that best viewing is at a 45 degree angle away from the radiant, but we maintain that meteors can appear anywhere in the sky. Pair up with a friend or two and watch in opposite directions to increase your meteor-spotting chances.
We also like to keep a set of binoculars handy to examine those smoke trains left by bright fireballs that may persist seconds after streaking across the sky.
And speaking of which, there has also been some spirited discussion over the past week as to whether or not the Perseids produce more fireballs than any other shower. I certainly remember seeing several memorable fireballs from this shower over the years, although the Geminids, Leonids and Taurids can be just spectacular on active years. The stated r value of the Perseids is one of the lowest at 2.2, suggesting a statistically high percentage of fireballs.
And in the realm of the strange and the curious, here are just a few phenomena to watch/listen for on your Perseid vigil;
– Can you “hear” meteors? Science says that sounds shouldn’t carry through the tenuous atmosphere above 50 kilometres up, and yet reports of audible meteors as a hiss or crackle persist. Is this an eye-brain illusion? Researchers in 1988 actually studied this phenomenon, which is also sometimes reported during displays of aurora. If there’s anything to it, the culprit may be the localized generation of localized electrophonic noises generated by Extra/Very Low Frequency electromagnetic radiation.
– Can meteor streaks appear colored? Green is often the top reported hue.
– Can meteors appear to “corkscrew” during their trajectory, or is this an illusion?
A Perseid very near the shower radiant during the 2012 shower. (Photo by author).
Wide-field photography is definitely a viable option during meteor showers. Just remember to bring extra charged batteries, as long exposure times will drain modern DSLRs in a hurry!
And did you know: you can even “listen” to meteor pings on an FM radio or portable TV? This is a great “rain check” option!
And there’s still real science to be done in the world of meteor shower studies. The International Meteor Organization welcomes counts from volunteers… and be sure to Tweet those Perseid sightings to #Meteorwatch.
Also be sure to check out the UK Meteor Observation Network, which has just launched their live site with streaming images of meteors as they are recorded.
Good luck, clear skies, and let the late 2013 meteor shower season begin!
-And be sure to post those Perseid pics to the Flickr forum on Universe Today… we’ll be doing photo essay roundups from observers around the world!
It’s time for another Weekly Space Hangout, where we give you a rundown of the big space news stories of the week, from a team of scientists and space journalists.
We record the Weekly Space Hangout live on Google+ every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch the show live here on Universe Today, or the archived version on YouTube.
Looking east from latitude 30 north on August 3rd, 30 minutes before sunrise. (Created by the author in Stellarium).
Can you feel the heat?
It’s not just your imagination. The northern hemisphere is currently in the midst of the Dog Days of Summer. For many, early August means hot, humid days and stagnant, sultry nights.
The actual dates for the Dog Days of Summer vary depending on the source, but are usually quoted as running from mid-July to mid-August. The Old Farmer’s Almanac lists the Dog Days as running from July 3rd through August 11th.
But there is an ancient astronomical observation that ties in with the Dog Days of Summer, one that you can replicate on these early August mornings.
The sky was important to the ancients. It told them when seasons were approaching, when to plant crops, and when to harvest. Ancient cultures were keen observers of the cycles in the sky. Cultures that were “astronomically literate” had a distinct edge over those who seldom bothered to note the goings on overhead.
The flooded Temple of Isis on the island of Philae circa 1905. (Credit: Wikimedia Commons under an Attribution-Share Alike 2.5 license. Author H.W. Dunning).
Sirius was a key star for Egyptian astronomers. Identified with the goddess Isis, the Egyptian name for Sirius was Sopdet, the deification of Sothis. There is a line penned by the Greco-Roman scholar Plutarch which states:
“The soul of Isis is called ‘Dog’ by the Greeks.”
Political commentary? A mis-translation by Greek scholars? Whatever the case, the mythological transition from “Isis to Sothis to Dog Star” seems to have been lost in time.
These astronomer-priests noted that Sirius rose with the Sun just prior to the annual flooding of the Nile. The appearance of a celestial object at sunrise is known as a heliacal rising. If you can recover Sirius from behind the glare of the Sun, you know that the “Tears of Isis” are on their way, in the form of life-giving flood waters.
Sopdet as the personification of Sirius (note the star on the forehead) Wikimedia Commons image under an Attribution Share Alike 3.0 license. Author Jeff Dahl).
In fact, the ancient Egyptians based their calendar on the appearance of Sirius and what is known as the Sothic cycle, which is a span of 1,461 sidereal years (365.25 x 4) in which the heliacal rising once again “syncs up” with the solar calendar.
It’s interesting to note that in 3000 BC, the heliacal rising of Sirius and the flooding of the Nile occurred around June 25th, near the summer solstice. This also marked the Egyptian New Year. Today it occurs within a few weeks of August 15th, owing to precession. (More on that in a bit!)
By the time of the Greeks, we start to see Sirius firmly referred to as the Dog Star. In Homer’s Iliad, King Priam refers to an advancing Achilles as:
“Blazing as the star that cometh forth at Harvest-time, shining forth amid the host of stars in the darkness of the night, the star whose name men call Orion’s Dog”
The Romans further promoted the canine branding for Sirius. You also see references to the “Dog Star” popping up in Virgil’s Aenid.
Over the years, scholars have also attempted to link the dog-headed god Anubis to Sirius. This transition is debated by scholars, and in his Star Names: Their Lore and Meaning, Richard Hinckley Allen casts doubt on the assertion.
Sirius as the shining “nose” of the constellation Canis Major. (Created by the author using Starry Night).
Ancient cultures also saw the appearance of Sirius as signifying the onset of epidemics. Their fears were well founded, as summer flooding would also hatch a fresh wave of malaria and dengue fever-carrying mosquitoes.
Making a seasonal sighting of Sirius is fun and easy to do. The star is currently low to the southeast in the dawn, and rises successively higher each morning as August rolls on.
The following table can be used to aid your quest in Sirius-spotting.
Latitude north
Theoretical date when Sirius can 1st be spotted
32°
August 3rd
33°
August 4th
34°
August 5th
35°
August 6th
36°
August 7th
37°
August 8th
38°
August 9th
39°
August 10th
40°
August 11th
41°
August 12th
42°
August 13th
43°
August 14th
44°
August 15th
45°
August 16th
46°
August 17th
47°
August 18th
48°
August 19th
49°
August 20th
50°
August 21st
Thanks to “human astronomical computer extraordinaire” Ed Kotapish for the compilation!
Note that the table above is perpetual for years in the first half of the 21st century. Our friend, the Precession of the Equinoxes pivots the equinoctial points to the tune of about one degree every 72 years. The Earth’s axis completes one full “wobble” approximately every 26,000 years. Our rotational pole only happens to be currently pointing at Polaris in our lifetimes. Its closest approach is around 2100 AD, after which the north celestial pole and Polaris will begin to drift apart. Mark your calendars—Vega will be the pole star in 13,727 AD. And to the ancient Egyptians, Thuban in the constellation Draco was the Pole Star!
The Colossi of Memnon Near Luxor, just one of the amazing architectural projects carried out by the ancient Egyptians. (Photo by author).
Keep in mind, atmospheric extinction is your enemy in this quest, as it will knock normally brilliant magnitude -1.46 Sirius a whopping 40 times in brightness to around magnitude +2.4.
Note that we have a nice line-up of planets in the dawn sky (see intro chart), which are joined by a waning crescent Moon this weekend. Jupiter and Mars ride high about an hour before sunrise, and if you can pick out Mercury at magnitude -0.5 directly below them, you should have a shot at spotting Sirius far to the south.
And don’t be afraid to “cheat” a little bit and use binoculars in your quest… we’ve even managed on occasion to track Sirius into the broad daylight. Just be sure to physically block the Sun behind a building or hill before attempting this feat!
Of course, the heliacal rising of Sirius prior to the flooding of the Nile was a convenient coincidence that the Egyptians used to their advantage. The ancients had little idea as to what they were seeing. At 8.6 light-years distant, Sirius is the brightest star in Earth’s sky during the current epoch. It’s also the second closest star visible to the naked eye from Earth. Only Alpha Centauri, located deep in the southern hemisphere sky is closer. The light you’re seeing from Sirius today left in early 2005, back before most of us had Facebook accounts.
Sirius also has a companion star, Sirius B. This star is the closest example of a white dwarf. Orbiting its primary once every 50 years, Sirius B has also been the center of a strange controversy we’ve explored in past writings concerning Dogon people of Mali.
Sirius B is difficult to nab in a telescope, owing to dazzling nearby Sirius A. This feat will get easier as Sirius B approaches apastron with a max separation of 11.5 arc seconds in 2025.
Some paleoastronomers have also puzzled over ancient records referring to Sirius as “red” in color. While some have stated that this might overturn current astrophysical models, a far more likely explanation is its position low to the horizon for northern hemisphere observers. Many bright stars can take on a twinkling ruddy hue when seen low in the sky due to atmospheric distortion.
Let the Dog Days of Summer (& astronomy) begin! (Photo by author).
All great facts to ponder during these Dog Days of early August, perhaps as the sky brightens during the dawn and your vigil for the Perseid meteors draws to an end!
There’s a potential “cometary graveyard” of inactive comets in our solar system wandering between Mars and Jupiter, a new Colombian research paper says. This contradicts a long-standing view that comets originate on the fringes of the solar system, in the Oort Cloud.
Mysteriously, however, 12 active comets have been seen in and around the asteroid belt. The astronomers theorize there must be a number of inactive comets in this region that flare up when a stray gravitational force from Jupiter nudges the comets so that they receive more energy from the Sun.
The researchers examined comets originating from the main asteroid belt between Mars and Jupiter, a spot where it is believed there are only asteroids (small bodies made up mostly of rock). Comets, by contrast, are a mixture of rocks and ice. The ice melts when the comet gets close to the sun, and can form spectacular tails visible from Earth. (Here’s more detail on the difference between a comet and an asteroid.)
This illustration shows three views of cometary activity. Top: The accepted view of comets, showing them coming from the outer solar system. Middle: The new proposal, saying some could come from the asteroid belt between Mars and Jupiter. Bottom: How the asteroid belt comets could have appeared during the early solar system’s history. Credit: Ignacio Ferrin / University of Antioquia
“Imagine all these asteroids going around the Sun for aeons, with no hint of activity,” stated Ignacio Ferrín, who led the research and is a part of the University of Antioquia in Colombia.
“We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent.”
The team believes this zone was far more active millions of years ago, but as the population got older they got more quiet.
“Twelve of those rocks are true comets that were rejuvenated after their minimum distance from the Sun was reduced a little,” the researchers stated.
“The little extra energy they received from the Sun was then sufficient to revive them from the graveyard.”
Astronaut Charles Duke collecting samples during Apollo 16. Credit: NASA.
Ask someone if they know the names of the astronauts who have walked on the Moon, and most people would be able to list Neil Armstrong, and maybe even Buzz Aldrin. But can you name the rest of the Apollo astronauts who made it down to the lunar surface? How many people have walked on the Moon?
In total twelve people have walked on the Moon. Besides Neil Armstrong and Buzz Aldrin – who were the first two astronauts to leave their bootprints on the Moon — there were also Pete Conrad, Alan Bean, Alan Shepard, Edgar Mitchell, David Scott, James Irwin, John Young, Charles Duke, Eugene Cernan, and Harrison Schmitt.
Interestingly, out of the dozen people who walked on the Moon, no one ever did it more than once.
The HiRISE Camera on the Mars Reconnaissance Orbiter captured the Curiosity rover descending on its parachute to land on Mars. Credit: NASA/JPL/Arizona State University.
Whew — the past year flew by fast! Can you believe it’s almost been a year already since the Mars Science Laboratory rover Curiosity thrilled the world with its nail-biting, sky-craning, engineer-high-fiving landing on Mars on August 6, 2012? Now for something even faster, here you can see what Curiosity has done since landing — where she’s roved, drilled, shook, and captured the views in this sped-up look at her travels, explorations and discoveries.
And since you can never see the landing highlight video too many times, we’ve posted it below:
An idea that really captures my imagination is what kinds of future civilizations there might be. And I’m not the only one. In 1964, the Soviet astronomer Nikolai Kardashev defined the future of civilizations based on the amount of energy they might consume.
A Type I civilization would use the power of their entire planet. Type II, a star system, and a Type III would harness the energy of an entire galaxy. It boggles the mind to think about the engineering required to rearrange the stars of an entire galaxy.
Is it possible to move a star? Could we move the Sun?
This idea was first proposed by physicist Dr. Leonid Shkadov in his 1987 paper, “Possibility of controlling solar system motion in the galaxy”.
Here’s how it works.
A future alien civilization would construct a gigantic reflective structure on one side of their star. Light from the star would strike this structure and bounce off, pushing it away.
If this reflective structure had enough mass, it would also attract the star with its gravity.
The star would be trying to push the structure away, but the structure would be pulling the star along with it.
If a future civilization could get this in perfect balance, it would be able to “pull” the star around in the galaxy, using its own starlight as thrust. At first, you wouldn’t get a lot of speed. But by directing half the energy of a star, you could get it moving through the galaxy.
Over the course of a million years, you would have changed its velocity by about 20 meters/second. The star would have traveled about 0.3 light years, less than 10% of the way to Alpha Centauri. Keep it up for a billion years and you would be moving a thousand times faster. Allowing you to travel 34,000 light years, a significant portion of the galaxy.
Imagine a future civilization using this technique to move their stars to better locations, or even rearranging huge portions of a galaxy for their own energy purposes.
This may sound theoretical, but Duncan Forgan, from the University of Edinburgh suggests a practical way to search for aliens moving their stars. According to him, you could use planet-hunting telescopes like Kepler to detect the bizarre light signatures we’d see from a Shkadov Thruster. There’s nothing in the laws of physics that says it can’t happen.
It’s fun to think about, and gives us another way that we could search for alien civilizations out there across the galaxy.
