What a photo! If you looked to the skies last night (January 21st), you may have noticed a bright point of light nearly on top of the Moon. That was Jupiter! Last night was the closest they will come (an event called “conjunction”) until 2026.
Their nearly intersecting “paths” through the sky are only due to our Earthly perspective, of course. Many things in the night sky will appear next to each other if we just wait long enough. What’s especially cool about this photograph is that it captures three levels of astronomical complexity in one image.
First we have our terrestrial satellite, Luna, with the “terminator” line of day/night stretched across a large, dark volcanic plain known as the “Ocean of Storms”, which is an awesome name for a volcanic plain. The next brightest image is Jupiter, our solar system’s largest planet/failed star. And those dots around Jupiter? Those are three of its Galilean moons! The photographer’s Facebook page says there’s four moons of Jupiter in this shot, but I only see three. If we are seeing them in their increasing distance from Jupiter (and that’s a big if, since perspective can play tricks on us), they are probably Io, Europa, and Ganymede.
A great list of famous scientists to get started on a history of astronomy unit.
Throughout human history, scientists have struggled to understand what they see in the universe. Famous astronomers — many of them great scientists who mastered many fields — explained the heavens with varying degrees of accuracy. Over the centuries, a geocentric view of the universe — with Earth at the center of everything — gave way to the proper understanding we have today of an expanding universe in which our galaxy is but one of billions. On this list are some of the most famous scientists from the early days of astronomy through the modern era, and a summary of some of their achievements.
When most people believed the world was flat, the notable Greek mathematician, astronomer and geographer Eratosthenes (276 BCE- 195 BCE) used the sun to measure the size of the round Earth. His measurement of 24,660 miles (39,690 kilometers) was only 211 miles (340 km) off the true measurement.
The ancient Greek astronomer and mathematician Claudius Ptolemy (AD 90- 168) set up a model of the solar system in which the sun, stars, and other planets revolved around Earth.
Persian astronomer Abd al-Rahman al-Sufi (903-986), known as Azophi to Westerners, made the first known observation of a group of stars outside of the Milky Way, the Andromeda galaxy.
In 16th century Poland, astronomer Nicolaus Copernicus (1473-1543) proposed a model of the solar system that involved the Earth revolving around the sun. The model wasn’t completely correct but it eventually changed the way many scientists viewed the solar system.
Using detailed measurements of the path of planets kept by Danish astronomer Tycho Brahe, Johannes Kepler (1571-1630) determined that planets traveled around the sun not in circles but in ellipses. In so doing, he calculated three laws involving the motions of planets that astronomers still use in calculations today.
Born in Italy, Galileo Galilei (1564-1642) is often credited with the creation of the optical telescope, though in truth he improved on existing models. The astronomer turned the new observational tool toward the heavens, where he discovered the four primary moons of Jupiter (now known as the Galilean moons), as well as the rings of Saturn. Though a model of the Earth circling the sun was first proposed by Copernicus, it took some time before it became widely accepted.
Dutch scientist Christiaan Huygens (1629-1695) proposed the earliest theory about the nature of light, a phenomena that puzzled scientists for hundreds of years. His improvements on the telescope allowed him to make the first observations of Saturn’s rings and to discover its moon, Titan.
Building on the work of those who had gone before him, English astronomer Sir Isaac Newton (1643-1727) is most famous for his work on forces, specifically gravity. He calculated three laws describing the motion of forces between objects, known today as Newton’s laws.
In the early 20th century, German physicist Albert Einstein (1879-1955) became of of the most famous scientists ever after proposing a new way of looking at the universe that went beyond current understanding. Einstein suggested that the laws of physics are the same throughout the universe, that the speed of light in a vacuum is constant, and that space and time are linked in an entity known as space-time, which is distorted by gravity.
At the same time Einstein was expanding man’s view of the universe, American astronomer Edwin Hubble (1899-1953) calculated that a small blob in the sky existed outside of the Milky Way. Prior to his observations, the discussion over the size of the universe was divided as to whether or not only a single galaxy existed. Hubble went on to determine that the universe itself was expanding, a calculation which later came to be known as Hubble’s law.
American astronomer Carl Sagan (1934-1996) may not have been a great scientists in comparison to some on this list, but he is one of the most famous astronomers. Sagan not only made important scientific studies in the fields of planetary science, he also managed to popularized astronomy more than any other individual. His charismatic teaching and boundless energy impacted people around the world as he broke down complicated subjects in a way that interested television viewers even as he educated them.
Stephen Hawking (born 1942) has made many significant insights into the field of cosmology. He proposed that, as the universe has a beginning, it will likely also end. He also suggested that it has no boundary or border. .
Other astronomers that achieved significant discoveries and are often mentioned among the greats:
Italian astronomer Giovanni Cassini (1625-1712) measured how long it took the planets Jupiter and Mars to rotate, as well as discovering four moons of Saturn and the gap in the planet’s rings. When NASA launched a satellite to orbit Saturn and its moons in 1997, it was fittingly dubbed Cassini.
Edmond Halley (1656-1742) was the British scientist who reviewed historical comet sightings and proposed that the comet which appeared in 1456, 1531, 1607, and 1682 were all the same, and would return in 1758.
French astronomer Charles Messier (1730-1817) composed a database of objects known at the time as “nebula,” which included 103 objects at its final publication, though additional objects were added based on his personal notes. Many of these objects are often listed with their catalog name, such as the Andromeda Galaxy, known as M31.
British astronomer William Herschel (1738-1822) cataloged over 2,500 deep sky objects. He also discovered Uranus and its two brightest moons, two of Saturn’s moons, and the Martian ice caps. William trained his sister, Caroline Herschel (1750-1848), in astronomy, and she became the first woman to discover a comet, identifying several over the course of her lifetime.
Henrietta Swann Leavitt (1868-1921)was one of several women working as a “computer” for Edwin Hubble at Harvard college, identifying images of variable stars on photographic plates. She discovered that the brightness of a special flashing star known as a Cepheid variable was related to how often it pulsed.
American astronomer Harlow Shapley (1885-1972) calculated the size of the Milky Way galaxy and general location of its center. He argued that the objects known as “nebula” lay within the galaxy, rather than outside of it, and in 1920 participated in the “Great Debate”.
Frank Drake (born 1930) is one of the pioneers in the search for extraterrestrial intelligence. He was one of the founders of the Search for Extraterrestrial Intelligence (SETI) and the deviser of the Drake equation, a mathematical equation used to estimate the number of extraterrestrial civilizations in the Milky Way galaxy able to be detected.
American astronomer William K. Hartmann (born 1939) put forth the most widely accepted theory on the formation of the moon in 1975. He proposed that, after a collision with a large body scooped, debris from the Earth coalesced into the moon.
—Nola Taylor Redd
The conjunction offers a chance to see how quickly the moon moves from night to night.
Look toward the southeast on Thursday night (THAT’S TONIGHT!!) about an hour after sunset, and you will behold a rare and beautiful sight, a triple conjunction of the moon, the planet Saturn, and the bright star Spica.
A conjunction occurs when two or more astronomical objects are close together in the sky. In reality they are far apart in space; their closeness is just an effect of perspective. In astrology such close encounters are supposed to cause serious effects, but astronomers know that conjunctions are nothing more than a beautiful sight and a photo opportunity.
In 2010, a star 127 light-years away stunned the world — it had become the largest star system beyond our own, playing host to five, possibly seven, alien worlds. Now, the star (called HD 10180) is back in the headlines; it may actually have nine exoplanets orbiting it.
Interestingly, HD 10180 is a yellow dwarf star very much like the sun, so this discovery has drawn many parallels with our own Solar System. It is a multi-planetary system surrounding a sun-like star.
It is believed that one of HD 10180’s exoplanets is small — although astronomers only know the planets’ masses, not their physical size or composition. The smallest world weighs-in at 1.4 times the mass of Earth, making it a “super-Earth.”
As the evening twilight deepens around 8:30 p.m. local time Tuesday night (April 3), check out the southeast sky. Weather permitting, a waxing gibbous moon will be shining bright, but it won’t be alone.
Situated well above the moon will be two bright “stars.” I’ve placed the word stars in quote marks, because one of those stars is in reality a planet: the so-called Red Planet, Mars.
The planet will form a cosmic triangle with the moon, Mars and bright star Regulus. The arrangement can be seen in the sky map of Mars accompanying this planet viewing guide.
Space weather in our solar system has been rather unsettled of late, and some of our tenacious robotic interplanetary explorers have been feeling the impact of the sun’s temper tantrums. The European Space Agency’s Venus Express orbiter suffered a particularly nasty solar sucker-punch, temporarily blinding one of its navigational systems.
The solar radiation hit Venus’ orbit on March 7 (Tuesday) after the sun had belched out a series of solar flares and coronal mass ejections (CMEs). This radiation uptick knocked-out Venus Express’ startracker cameras (including the backup camera), causing them to lose sight of stars the spacecraft uses to orient itself.
- March 13, 2012 for Wired
Neil deGrasse Tyson is one of the very few people smart enough, knowledgeable enough, charming enough, and, yes, famous enough that he might just be the best spokesperson for science alive. He’s certainly the best spokesperson for American space exploration, a subject that has never needed advocates more than it does today. I recently had the chance to talk with Dr. Tyson about these matters and much more.
The largest solar storm in five years — spawned by a double whammy of flares from the sun — has engulfed Earth, but scientists say the planet has lucked out so far.
(we can’t get enough of this solar storm. or those pics!)