Astrophotographers were out in full force this weekend to try and capture the bonanza of comets now visible in the early morning skies! You’ll need a good-sized telescope to see these comets for yourself, however, but with the Moon now waning means darker skies and better observing conditions. Above is an absolutely gorgeous image of Comet ISON taken by Damian Peach. See below for more images of not only Comet ISON, but also Comet Encke, Comet Lovejoy and Comet LINEAR — now in outburst.
In fact, one of our “regular” contributors, John Chumack, captured all four comets in one morning, on Saturday October 26!
Here’s what John said about his Comet ISON image: “The tail extends off the frame it is at least 20 arc minutes long now and the coma is still around 3-4 arc minutes in diameter. The comet is looking good at about 12th magnitude and continues to slowly brighten, just 30 more days to perihelion — closest point to the Sun. Hopefully it puts on a good show for all of December too!”
And Comet Linear 2012 X1 was at 14th magnitude, but now in outburst, John said, “it is over 100-fold brighter at 8th magnitude and expanding! It was low on the horizon at dawn, and tough to get. It just cleared the trees at 7:07am in bright dawn light! I managed a couple of quick shots before my CCD was flooded completely with light!”
Of Comet Lovejoy, John said, “I found it has developed a faint long tail…it is at least 12 arc minutes in length and the comet’s coma is now around 6 arc minutes in diameter. I already notified Terry Lovejoy in Australia and he was excited to hear his comet has developed a new tail!”
Here’s a timelapse video from John of Comet Lovejoy moving through the constellation of Canus Minor:
Here’s a view from a smaller telescope from Tom Wildoner, to give a better idea of what “most of us” would see with our humbler telescopes!
Even NASA astronomers were out trying to take images of these comets. Here’s an image taken from NASA’s Marshall Spaceflight Center:
NASA explains the image:
In the early morning of Oct. 25 (6:45 a.m. EDT), NASA’s Marshall Space Flight Center in Huntsville, Ala., used a 14″ telescope to capture this image of Comet C/2012 S1 (ISON), which is brightening as it approaches the sun. The comet shines with a faint green color just to the left of center. The diagonal streak right of center was caused by the Italian SkyMed-2 satellite passing though the field of view. At magnitude 8.5, the comet is still too faint for the unaided eye or small binoculars, but it’s an easy target in a small telescope.
At this time of this image, ISON was located in the constellation of Leo the Lion, some 132 million miles from Earth and heading in toward the sun at 87,900 miles per hour.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
It’s almost upon us. The final eclipse of 2013 occurs this coming weekend on Sunday, November 3rd. This will be the fifth eclipse overall, and the second solar eclipse of 2013. This will also be the only eclipse this year that features a glimpse of totality.
This eclipse is of the rare hybrid variety— that is, it will be an annular eclipse along the very first 15 seconds of its track before transitioning to a total as the Moon’s shadow sweeps just close enough to the Earth to cover the disk of the Sun along the remainder of its track.
How rare are hybrid solar eclipse? Of the 11,898 solar eclipses listed over a 5,000 year span from 1999 BC to 3000 AD in Fred Espenak’s Five Millennium Catalog of Solar Eclipses, only 569, or 4.8% are hybrids.
Who can see this eclipse?
People from northern South America, across the U.S. Eastern Seaboard and up through the Canadian Maritimes will see a brief partial solar eclipse finishing up around 30 minutes after local sunrise. The brief annular “ring of fire” portion of the eclipse begins at sunrise just ~1,000 kilometres east of Jacksonville, Florida, as it races eastward across the Atlantic. See our timeline, below.
Nearly all of Africa and the southern Mediterranean region including Spain will see partial phases of the eclipse, while greatest totality occurs just off of the coast of Liberia and heads for first landfall on the African continent over Wonga Wongue Reserve in Gabon. At this point, the duration of totality will already have shrunk back down to 1 minute and 7 seconds. The shadow of the Moon will then cross central Africa, headed for a short but brilliant sunset total eclipse over Uganda, Ethiopia, Kenya and Somalia.
This particular eclipse part of saros series 143 and is member 23 of the 72 eclipses in the cycle. The first eclipse in this saros occurred on March 7th, 1617, and the last one will occur on April 23rd, 2897.
Saros 143 also has a checkered place in eclipse history. The last eclipse in this series crossed south eastern Asia on October 24th, 1995.
The first detailed picture of a solar eclipse was also taken of a saros 143 member on July 28, 1851. And one saros later, a total solar eclipse on August 7th, 1869 may have saved the butt of astronomer and explorer George Davidson while traversing the wilds of Alaska. And one more saros period later, Dmitri Mendeleev (he of the modern periodic table) observed the total solar eclipse of August 19th, 1887 from a balloon.
We’ve compiled a brief worldwide timeline for the November 3rd hybrid eclipse. Keep in mind, the shift back off of Daylight Saving Time occurs on the same morning as the eclipse for North America, putting the U.S. East Coast once again back to -5 hours off of Universal Time (UT):
10:04 UT: The partial phases of the eclipse begin.
11:05:17 UT: annular phases of the eclipse begin.
11:05:36 UT: The eclipse transitions from an annular to a total along its track.
12:46: The point of greatest eclipse, occurring off of the SW coast of Liberia along the coast of Africa. The path will be 57 kilometres wide at this point with a maximum duration for totality at 1 minute & 40 seconds.
14:27 UT: The total phases of the eclipse end.
15:28 UT: Partial phases end.
Remember that solar safety is paramount while observing an eclipse during all partial phases. This is especially critical, as millions of viewers along the U.S. East Coast are poised to catch the eclipse at sunrise over the Atlantic on Sunday. Use only glasses designed specifically for eclipse viewing or welder’s glass #14. One project headed by Astronomers Without Borders is also working to provide eclipse glasses to schools in Africa.
Projecting the Sun onto a wall or a piece of paper is also a safe method to observe the eclipse. Construction of a Sun Gun, a pinhole projector, or even using a spaghetti strainer or colander to project the partially eclipsed sun are all fun projects to try.
Shooting pictures of the rising eclipse is also possible using a DSLR. To capture the disk of the Sun plus an outline of the foreground, you’ll want to use a combination of low ISO 100 and a fast shutter speed (1/4000 or faster) and a zoom lens of at least 200mm or greater. Keep in mind, DO NOT look at the Sun through the camera’s view finder— simply set the focus to infinity and aim via projection. It’s worth practicing your technique a morning or two prior to the main event!
As the partial phase of the eclipse progresses, keep an eye out for “tiny crescents” that may litter the ground. These are caused by gaps in things such as leaves, latticework, etc that may act as natural “pinhole projectors”. Those lucky enough to stand in the path of totality may snare a look at shadow bands sweeping across the landscape as totality approaches, as well as catch a brief glimpse of Baily’s Beads and the pearly white corona of the Sun.
Totality will last less than a minute across most of central Africa, giving viewers a very hurried view before partial phases commence once more. Venus will be easily visible at magnitude -4.4 just 47 degrees east of the Sun. Unfortunately, prospects aren’t great for air or seaborne viewers in the mid-Atlantic to catch sight of comet ISON during the frenzied moments of totality, which will sit 50 degrees from the Sun between magnitude +7 & +8.
Weather prospects are an all-important consideration when planning for an eclipse. Jay Anderson maintains an outstanding site with projections tailor-made for each eclipse. For the U.S. East Coast, clear skies right down to the crucial eastern horizon will be key!
A recent surge in piracy off of the West Coast of Africa may also factor into travel considerations for eclipse chasers. You can actually monitor such activities on the high seas now in near real time. Perhaps one could take a page from Mark Twain’s A Connecticut Yankee in King Arthur’s Court, and impress any would-be-brigands with the glory of an impending solar eclipse…
Unfortunately, the International Space Station will have an orbit nearly perpendicular to the Earth-Moon-Sun syzygy, and won’t lend itself to any great prospects of a transit during the partial phases of the eclipse. ESA’s Proba-2 and JAXA’s Hinode will, however, see several partial eclipses from orbit:
Sunspot activity has also been on the upswing as of late, making for a photogenic Sun heading into the partial phases of the eclipse. A well-placed, naked eye Coronal Mass Ejection on the solar limb also isn’t out of the question. Eclipse historian and expert Michael Zeiler notes that a CME last occurred during a total solar eclipse way back in 1860.
Totality for this eclipse passes over some wild and largely wifi free areas; few plans to broadcast the eclipse live have surfaced thus far.
Slooh plans a broadcast, as did a proposed Indiegogo project whose current status is unclear. BRCK also plans to broadcast the eclipse live from the shores of Lake Turkana, Kenya. Got plans to webcast even the partial phases of the eclipse? Let us know!
And speaking of eclipse chasing, we plan on heading to the Florida Space Coast Sunday morning at o’dark thirty to nab the partial sunrise eclipse over the Atlantic.
And as always, the question posed immediately after totality is: when’s the next one? Well, the next annular eclipse graces Australia on April 29th, 2014. The U.S. will also see a partial solar eclipse on October 23rd next year… but totality will not touch the surface of our fair planet until a high Arctic eclipse on March 20th, 2015.
Good luck, clear skies, and safe journeys to all who are chasing after this one near and far, and don’t forget to post those pics to Universe Today’s Flickr page!
-See more of Michael Zeiler’s work at Eclipse Maps.
Although the Zodiac is best known for astrology nonsense, it has a purpose in astronomy too. The constellations of the Zodiac define the plane of the ecliptic: the region where the Sun, Moon and planets appear to travel through the sky. What are the constellations of the Zodiac, and how do astronomers use them as way points?
We record Astronomy Cast as a live Google+ Hangout on Air every Monday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch here on Universe Today or from the Astronomy Cast Google+ page.
To drum up publicity for the Google Lunar XPRIZE missions, the organization has produced a “dome film” about exploring the moon through the past to the future — and is giving away the product for free to dozens of dome theaters and planetariums worldwide.
Among Back To the Moon For Good’s first appearances will be the National Science Center at Leicester, United Kingdom on Nov. 6, and a United States premiere is on its way shortly. A full list of participating venues so far is at this website. The target audience for the show (which is designed for a wraparound theater) is elementary and secondary school students.
“It was Mercury, Gemini and Apollo that took the us into space, and ultimately to the moon, and this was incredibly exciting and was responsible for lots of folks going into science and technology over the years,” said Bob Weiss, who is XPRIZE’s president and executive producer of the film, in a Universe Today interview.
“We would like to provide a 21st century version of that, but as a new kind of space mission, more interactive and participatory,” he added, saying that social media and Internet websites would be a couple of ways people at home can stay engaged in the mission or missions to the moon. (That definitely wasn’t possible generally when Apollo 11, the first moon mission, landed in 1969!)
The narrator of the show is Tim Allen, an actor best known for the Home Improvementseries of the 1990s. Allen, by the way, is a fan of space himself (says Weiss) and also appeared in a 1999 parody science fiction film called Galaxy Quest. Weiss said the desire was to find somebody who was family-friendly, well-known and enthusiastic about the project.
By the way, loyal fans of Home Improvement will recall that astronauts appeared on the “Tool Time” segment of the show on several occasions, usually after Hubble Space Telescope repair missions. (NASA astronaut Ken Bowersox appeared three times himself, in 1994, 1996 and 1998.)
In Season 3 show “Reality Bytes” in 1994, Tim Allen’s character asked STS-61 commander Dick Covey what the difference was between repairs in space and repairs on Earth. “It’s actually a lot like using tools here on Earth. Except there’s no gravity, so you don’t have to worry about dropping a tool on your foot,” Covey quipped.
If “Tool Time” was taking place now, we wonder if Allen would also be interviewing private companies working on robotic and human spaceflight. XPRIZE is still chugging along well, Weiss said, and added some of the teams have signed launch contracts to send their robots to the moon. (He declined to provide many details, citing confidentiality reasons.)
“We have folks who have launch contracts to go to the moon, and another serious sign is when there is real flight hardware that is being built and tested. I have seen myself some of this hardware, and there are teams that are really racing to beat each other,” he said.
“There are approximately 20 teams around the world competing to do this. It has been an interesting competition, watching some teams drop off and some devolve and recombine with each other.”
Teams have until Dec. 31, 2015 to send a robotic spacecraft to the moon, travel 500 meters (whether on, below or above the surface), and transmit two “mooncasts” for Earth. At least $40 million in “incentive-based prizes” are up for grabs. We’ve covered a few of the concepts on Universe Today before, such as one team seeking to send robots into moon caves, and a college group trying to put a rover on the surface.
Universe Today and Royal Observatory Greenwich are pleased to offer one free copy of Astronomy Photographer of the Year: Collection Two!
Universe Today Review by Dave Dehetre
Astronomy Photographer of the Year is a large format glossy book that covers the Royal Observatory, Greenwich’s annual astrophotography competition. It covers the competition years from 2009 to 2012 and subject categories: Earth and Space, Our Solar System, Deep Space, Young Astronomy Photographer, People and Space, Best Newcomer, and Robotic Scope. It also includes a brief how-to primer on astrophotography which, while fine, seemed perfunctory and tacked on.
The book is organized by years and then by category, with nice double page section breaks and clear detailed info alongside each image. However, within each year, the categories aren’t delineated, either through typographic means, such as headers or section breaks, or through any indication alongside the images themselves. Usually the category was obvious enough, but it was somewhat confusing at times. Each category contains images by the winner, runner-up, and sometimes one or more ‘highly-commended’ entrants. Some categories also had other images without any designation of why they were included. This could be a typographic omission of some sort, or it could be that they were just additional entrants worthy of inclusion.
I was happy to see the consistently high caliber of work that came out of the competition. There isn’t one image in the book that was less than outstanding. I’ve spent many a night far out in the countryside doing astrophotography as a hobby, and I’ve never come up with an image to compare.
I was also happy to see the competition segmented into subject areas as well as the more expected age/experience categories. This seems to acknowledge that there are different metrics and merit for the broad scope of styles/subjects in astrophotography.
One other point worth mentioning is that I found that many of the astrophotographers presented were people I was already familiar with, some from Flickr, some from Youtube, and some from periodicals like Sky at Night. I knew these people, and not because they produce great images, but because they are some of the people I learned astrophotography from. I think this points out one of the great underlying aspects of astrophotography: that it is collaborative in nature. And I find it heartening that the people who share the most, who help others and communicate, seem to be the ones who do the best work and are the most successful.
I’m of two minds about Astronomy Photographer of the Year though. On the one hand, it’s very well done, beautiful, and stunning. Really everything you could ask for in a book on this subject. But against it, in part it is trying to document something (astrophotography) that is bigger and richer than can be captured in a book.
While the images are flawlessly presented, they lack the backlit brilliance provided by a computer screen, and they aren’t zoomable to view fine details. Many astrophotography images are available on-line at resolutions equivalent to wall-size if they were printed out.
There is also the problem of completeness. While the book is cover-to-cover with great images, in large part it is singular images from outstanding photographers who have dozens or hundreds of stunning images on-line. I found myself flipping a few pages at a time, and then being overcome with a desire to go search out a photographer’s other images. This is perhaps an inevitable outcome of the fact that the competition was conducted on-line (via Flickr), so it’s hard to see it as a negative.
So it really is a fantastic book, I love having it on my shelf, and I often flip through at random and find myself getting inspired, but I don’t think I would have searched it out for that purpose, and I’m not sure who the target customer is supposed to be. It seems incomplete and cursory, especially in the technical details, for someone already involved with the hobby and yet it has a price tag and scope that seem inconsistent with an introductory level book. It would make a great addition to a library collection.
~
If you want to purchase a copy of Astronomy Photographer of the Year: Collection Two, it is available on Amazon.com.
Universe Today and Royal Observatory Greenwich are pleased to be able to offer one free copy of Astronomy Photographer of the Year: Collection Two to our readers. In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, November 4, 2013. If this is the first time you’re registering for a giveaway from Universe Today, you’ll receive a confirmation email immediately where you’ll need to click a link to be entered into the drawing. For those who have registered previously, you’ll receive an email later where you can enter this drawing.
Remember that planet discovered near Alpha Centauri almost exactly a year ago? As you may remember, it’s the closest system to Earth, making some people speculate about how quickly we could get a spacecraft in that general direction. Four light years is close in galactic terms, but it’s a little far away for the technology we have now — unless we wanted to wait a few tens thousands of years for the journey to complete.
Meanwhile, we can at least take pictures of that star system. The Hubble Space Telescope team has released a new picture of Alpha Centauri’s sister star, Proxima Centauri. While Proxima is technically the closest star to Earth, it’s too faint to be seen by the naked eye, which is not all that surprising given it is only an eighth of the sun’s mass. Sometimes, however, it gets a little brighter.
“Proxima is what is known as a ‘flare star’, meaning that convection processes within the star’s body make it prone to random and dramatic changes in brightness.” stated the Hubble European Space Agency Information Centre.
“The convection processes not only trigger brilliant bursts of starlight but, combined with other factors, mean that Proxima Centauri is in for a very long life.”
How long? Well, consider the following: the universe is about 13.8 billion years old and Proxima is expected to remain in middle age for another four TRILLION years. Plenty of time for us to send a spacecraft over there if we’re patient enough. (The universe itself is expected to last a while, as Wise Geek explains.)
The picture was nabbed with Hubble’s Wide Field and Planetary Camera 2, with neighbouring stars Alpha Centauri A and B out of the frame.
Go from the highest volcano to the deepest canyon on Mars in this great new complication video from images taken by ESA’s Mars Express. The data shown here was gathered from the nearly 12,500 orbits by the Mars Express spacecraft since its arrival at the Red Planet in late 2003, and used to create digital topographic models of almost the entire surface of the planet. Not only does this provide unique and stunning visualization to create these “flyovers” of various locals on Mars, it also enables researchers to acquire new and surprising information about the evolution of the Red Planet.
The images in this movie were taken by the High Resolution Stereo Camera and the video was released by the DLR German Aerospace Center as part of the ten years of Mars Express celebrations in June 2013, and was just released online today.
Enjoy another recent Mars Express video, a flythrough of Hebes Chasma:
The Expedition 37 crew onboard the International Space Station closed the hatch and said goodbye to the ATV-4 “Albert Einstein” cargo ship early this morning, Oct. 28. Europe’s 4th Automated Transfer Vehicle undocked at 08:55 UTC (4:55 a.m. EDT). The cargo carrier was filled with trash and it will be deorbited on Nov. 2 for a destructive entry back into the Earth’s atmosphere over the Pacific Ocean. ATV-4 has been at the ISS since June 15, delivering more than 7 tons of food, fuel and supplies. Its departure helps prepare for more action at the ISS: the current Soyuz spacecraft docked at the station will be moved to a different location so that a new Soyuz can dock with three new crew members. The Soyuz TMA-11M is scheduled to launch on Nov. 6, 2013 with the Expedition 38/39 crew of Rick Mastracchio, Koichi Wakata, Mikhail Tyurin.
Some images of the undocking, below:
This photo was taken from Japan shorty after the undocking:
Hello Readers! We have a new book review and giveaway for your enjoyment: Star Trek Federation: The First 150 Years.
From the Publisher:
Star Trek Federation: The First 150 Years
For the first time, an ‘in universe’ history of Star Trek, complete with excerpts from Starfleet records and intergalactic intelligence, including James T. Kirk’s official biography and newly translated Klingon reports.
Star Trek Federation: The First 150 Years celebrates the 150th anniversary of the founding of the United Federation of Planets.
This unprecedented illustrated volume chronicles the pivotal era leading up to Humankind’s First Contact with Vulcan in 2063, the Romulan War in 2156, the creation of the Federation in 2161, and the first 150 years of the intergalactic democracy up until the year 2311. Meticulously researched, this account covers a multitude of alien species, decisive battles, and the technology that made the Age of Exploration possible. It includes field sketches, illustrations, and reproductions of historic pieces of art from across the Galaxy, along with over fifty excerpts from key Federation documents and correspondence, Starfleet records, and intergalactic intelligence.
David A. Goodmanhas spent the last 26 years writing for television. His credits include The Golden Girls, Star Trek: Enterprise, Futurama (where he wrote the Nebula Award nominated Star Trek homage “Where No Fan Has Gone Before”), and Family Guy where he was head writer for six years. This is his first book. He lives in Pacific Palisades, CA with his family.
You can purchase a copy of Star Trek Federation: The First 150 Years through Amazon.com.
Universe Today Review by Kristopher A. Poskey
Hypothetically, in the year 2347, young students throughout the Alpha Quadrant of The United Federation of Planets have found the book Star Trek Federation, The First 150 Years an exhilarating 167 page chronological review of exploration and diplomacy in space. Yet, here we are in the year 2013, reading as if we had survived to see the end of the first 150 years.Perhaps 27 year old David A. Goodman, Memory Alpha Historian, has travelled back in time to the year 2013 and brought this book back with him.
Goodman is well known for his work on “The Golden Girls”, “Family Guy”,” Futurama”, and ultimately his work on “Star Trek: Enterprise”. Goodman first publicly expressed his interest in Star Trek when he wrote, Where No Fan Has Gone Before, a well-known Futurama episode from the fourth season dedicated to Star Trek (it was nominated for the Nebula Award). Perhaps Goodman may even speak Klingon, but this episode showed just how vast Goodman’s knowledge was of Star Trek, its characters, and its history. Goodman says the inspiration for this book came from “The Star Trek Spaceflight Chronology” that was published in December, 1979. As its title suggests, the original book chronicles humans’ space ventures from Sputnik I to the events depicted in “Star Trek: The Motion Picture”.
Goodman’s new book begins on April 5, 2063 with the events surrounding “First Contact” and extends to the year 2311. The year 2311 marked the first 150 years of The Federation. As any good historian, Goodman not only told the stories that built the federation, but included minute details, allowing the reader to get a full grasp on what kinds of dynamic situations, the early pioneers faced. Goodman teamed up with 4 artists (Joe Corroney, Mark McHaley, Cat Staggs, and Jeff Carlisle) to add a plethora of illustrations that bring the history and its stories to life. Depictions of your favorite characters and pivotal moments truly add a new perspective to this captivating story. Excerpts from the Captain’s Log, as well as newspaper clippings are scattered throughout the book. Documents written in Klingon, Vulcan, Andorian, Romulan, Tellarite, and Coridan are included, along with their English translations. These and many other surprises lie within the pages of this sophisticated historical document.
If you’re an avid Trekkie, this book is a must-have for your collection (you may even learn a thing or two). If you’ve never been a huge Star Trek fan, this book will still appeal to you, not only in an emotional but also in a logical way. While the book is particularly broad about specifics, it focuses on the Federation as a whole, and the more widespread effects of decisions the leaders made. While we may have enjoyed the detail and the excitement in each episode of Star Trek, from our younger days, this book truly takes the story to a whole new level: by evaluating the entire galaxy and plotting the historical significance of various events that occurred. This book is a must read for Star Trek and science fiction fans alike.
Universe Today and Titan Books are pleased to be able to offer two free copies of Star Trek Federation to our readers. In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, November 4, 2013. If this is the first time you’re registering for a giveaway, you’ll receive a confirmation email immediately where you’ll need to click a link to be entered into the drawing. For those who have registered previously, you’ll receive an email later where you can enter this drawing.
It’s amazing to think that for the majority of human history, we had almost no understanding about the Sun. We didn’t know what it was made of, how it formed, or how it produced energy. We didn’t know how big it was, and we didn’t know how far away it was.
We orbit the Sun at a distance of about 150 million kilometers. This number is actually an average, since we follow an elliptical path. At its closest point, the Earth gets to 147 million km, and at its most distant point, it’s 152 million km.
Distances in the Solar System are so vast that astronomers use this distance as a standard for measurement, and so the average distance from the Earth to the Sun is called an astronomical unit. Instead of saying that Pluto is 5.87 billion kilometers away from the Sun, astronomers say that it’s 39 astronomical units, or AUs.
You might be surprised to know that the distance from the Sun to the Earth was only determined within the last few hundred years. There were just too many variables. If astronomers knew how big it was, they could figure out how far away it was, or vice versa, but both of these numbers were mysteries.
Ancient astronomers, especially the Greeks, tried estimating the distance to the Sun in several different ways: measuring the length of shadows on Earth, or comparing the size of the Moon and its orbit to the Sun. Unfortunately, their estimates were off at least by a factor of 10.
The key to figuring out the distance to the Sun came from observing Venus as it passed directly in front of the Sun. This rare event, known as a Transit of Venus, happens only twice every 108 years. Once devised, the best opportunities for taking this precise measurement came during the Venus transits of 1761 and 1769. Astronomers were dispatched to remote corners of the globe to observe the precise moment when Venus began to move in front of the Sun, and when it had moved completely across the surface.
By comparing these measurements, astronomers could use geometry to calculate exactly how far away the Sun is. Their initial calculations put the distance at 24,000 times the radius of the Earth. Not bad considering our modern measurement of 23,455 times the radius of the Earth.
Modern astronomers can use radar and laser pulses to calculate the distance to objects in the Solar System. For example, they fire an intense beam of radio waves at a distant object, like Mercury, and then calculate how long it takes for the waves to bounce off the planet and return to Earth. Since the speed of light is well known, the return travel time tells you how far away the planet is.
Astronomy has truly helped us find our place in the Universe. It nice to be living in a time when many of these big mysteries have been solved. I don’t know about you, but I can’t wait to see what’s around the corner of the next discovery.