Venus Kisses Saturn On Friday Jan. 8

On Friday, January 8, the planet Venus will appear to pass just 5 arc minutes north of the planet Saturn, That is a mere one-sixth of the diameter of the moon, a small enough distance to fit in the eyepiece of a powerful telescope.

On January 9, the planet Venus will appear to pass just north of the planet Saturn. Credit: Starry Night software.

This will be a rare opportunity to see two planets at the same time in a telescope’s narrow field of view. In a lifetime of observing the skies, I have seen such a close conjunction of two planets only two or three times. With the naked eye, sharp-eyed observers will be hard pressed to separate the two points of light.

Unfortunately for observers in North America, the point of closest conjunction will occur at 11 p.m. EST, while the planets are below the local horizon. For a skywatcher in New York, for example, the planets won’t clear the eastern horizon until 5 a.m. EST, at which time they will have separated so that they are 17 arc minutes apart, or slightly more than half the diameter of the moon. Even so, they will still fit in a telescope eyepiece.

Of course, this conjunction is something of an optical illusion. The two planets aren’t anywhere near each other in space, but merely appear close together from our perspective here on planet Earth.

Venus is currently on the far side of the Sun from Earth, 1.22 astronomical units distant (1.22 times the average distance from the Earth to the sun), so it appears similar to a gibbous moon.
Saturn is 10.79 astronomical units from Earth, nearly 9 times farther away than Saturn.

The two appear almost the same angular diameter: 14 arc seconds for Venus, 15 arc seconds for Saturn, yet in reality Saturn is actually almost 10 times the diameter of Venus. So Saturn’s greater distance balances out is larger size, and the two appear almost the same from Earth.

The most striking difference between the two is their difference in brightness. Venus is magnitude –4.0 on the upside-down brightness scale astronomers use, while Saturn is only magnitude +0.5, 4.5 magnitudes (or almost 100 times) fainter than Venus. This difference is mainly due to Venus’ closeness to the sun (0.72 astronomical units) compared to Saturn’s (9.55 astronomical units).

When you look for the twin planets just before dawn on Saturday morning, the first thing you will notice is Venus shining brightly in the southeastern sky. You will have to look closely to spot “tiny” Saturn just above and to the right of it.

If you own a planetarium program like Starry Night that lets you travel to other planets, check out the view Saturday morning from Saturn. You will see Earth and Venus in a close conjunction, Venus a narrow crescent from Saturn’s perspective, and Earth a rounded gibbous shape, since despite being close in the sky, they are actually on opposite sides of the sun, and lit by it quite differently.

Observing Saturn

On Friday, May 22, at 10 p.m. EDT, Saturn will be in opposition to the sun. This means that it will be directly opposite the sun in our sky. It will rise as the sun sets in the evening, shine brightly all night long, and set as the sun rises at dawn.

On May 22, Saturn reaches opposition with the Sun. It will be right on the border between Libra and Scorpius, just above the three stars which form the Scorpion’s claws. Credit: Starry Night software.

If you just look at the sky on a single night, everything seems quite static. But if you watch Saturn over a period of a few weeks and note its position against the background stars, you will see that it is in constant motion.

Currently Saturn is moving with what is called “retrograde motion,” from left to right against the background stars. This is actually an optical illusion caused by the Earth’s much more rapid movement around the sun. Once the Earth is well past Saturn in early August, Saturn will appear to reverse directions and begin moving in its true direction, from right to left.

This retrograde motion puzzled early skywatchers, who though the planets must go around it tiny circles called epicycles. This was because they incorrectly believed that the Earth was fixed in space and everything revolved around it, the “geocentric theory.” Once Copernicus made clear that the sun, not the Earth, was the center of the Solar System, the geometry of the planets’ motion became much simpler.

Saturn, like all the planets, is much smaller in angular size than most people realize. I once tried an experiment to see how much magnification was needed to see Saturn’s rings. With a binocular magnifying 10 times, Saturn looked just like a bright star. With a 15x binocular, I could just see a hint that Saturn was oval rather than round. It took a telescope magnifying 25 times to see Saturn’s true shape, though even then no detail was visible. I generally use magnifications of 150 to 250 times to see the details of Saturn and its ring system.

Saturn really has multiple rings, of which the brightest are the outer A ring and the inner B ring. The A ring is noticeably darker than the B ring, and the two are separated by the dark Cassini Division, named after 17th century Italian astronomer Giovanni Domenico Cassini, who was the first to observe it in 1675. Cassini also discovered four of Saturn’s five brightest moons.

The Cassini Division separates the A and B rings.

Titan, the largest and brightest of Saturn’s moons was discovered in 1655 by Dutch astronomer Christiaan Huygens. It is visible in even the smallest telescopes. It is the second largest moon in the Solar System (after Jupiter's moon Ganymede), the only moon to have a dense atmosphere, and the only moon other than our own to have been landed on by a spacecraft.

Huygens was also the first person to deduce that Saturn’s rings were flat circular objects in the plane of Saturn’s equator. Further study has shown that they are made up of thousands of tiny fragments of rock and ice. I once watched a star pass behind these rings, and the star continued to be visible, since there is more empty space that rock and ice in the rings, making them translucent.

Saturn’s smaller moons are worth looking for if you have a good telescope. The brighter ones are visible in a 90mm telescope. Because they are in constant motion around Saturn, you need a planetarium program like Starry Night to identify which ones are visible on a given night. Most of the bright moons move in the same plane as the rings, so appear to trace ovals around the planet.

In a telescope at about 150 power, Saturn is small but beautiful in its perfection, the jewel of the Solar System. Look around the planet for its brightest moons. Credit: Starry Night software.

Iapetus is a particularly interesting moon. Its orbit lies outside those of the other bright moons, and is tilted at an angle of 15 degrees compared to the other moons and the rings. Like all major moons in the Solar System, Iapetus always keeps one face permanently turned towards its planet. The side of Iapetus which leads it around in its orbit has encountered a large amount of debris, painting that face of the moon dark black. When that blackened side of Iapetus is facing Earth, at the moon’s greatest elongation east, it is almost two magnitudes fainter than when the trailing side of Iapetus is facing us, at greatest western elongation.

Right now Iapetus is close to its western elongation, so is at its brightest, magnitude 10.1. By greatest elongation east on June 27, it will be at its faintest, magnitude 11.9.

The globe of Saturn itself is rather bland when compared to its more active neighbor Jupiter. It shows a system of darker belts and brighter zones, but their contrast is muted compared to Jupiter. From time to time bright spots have been observed in Saturn’s cloud tops, but they have short lives compared to cloud features on Jupiter. In large telescopes, the polar regions of Saturn take on an olive green color.

It is interesting to observe the pattern of shadows on Saturn. The rings cast shadows on the globe of the planet, and the planet in turn casts its shadow on the rings. I have observed these shadows in a telescope as small as 90mm aperture under steady seeing conditions.

Whenever I observe Saturn in a telescope, I always take a few minutes to just sit back and admire its sheer beauty. Saturn was one of the first objects I looked at when I got my first telescope as a teenager, and I still recall the wonder I felt at witnessing this beauty for the first time with my own eyes: “It really has rings!”

If you'd like to follow along with NASA's New Horizons Mission to Pluto and the Kuiper Belt, please download our FREE Pluto Safari app.  It is available for iOS and Android mobile devices. Simulate the July 14, 2015 flyby of Pluto, get regular mission news updates, and learn the history of Pluto.

Simulation Curriculum is the leader in space science curriculum solutions and the makers of Starry Night, SkySafari and Pluto Safari. Follow the mission to Pluto with us on Twitter @SkySafariAstro, Facebook and Instagram. 

Saturn Through the Ages

On May 23rd, Saturn will reach opposition — the closest it will be to Earth in 2015.

Saturn, the original Load of the Rings.

Saturn can be viewed in the morning sky until May 23, when it moves into the evening sky. From November to the end of the year it will be behind the Sun.

Looking south-east on May 23, 2015 at 11:00 p.m. from mid-northern latitudes.

The rings are now widely open, making them easy to see in any telescope magnifying more than about 30x. Saturn’s largest moon Titan is readily visible in a small telescope, and several more moons may be seen in larger telescopes. At opposition, the planet’s equatorial angular diameter will be 19 arc seconds, its rings being 42 arc seconds across.

As you peer through your eyepiece and ponder the ringed planet with the benefit of our modern understanding of science, consider how perplexing Saturn must have been to ancient people whose instruments and grasp of nature were at their infancy.

Eyepiece view (10 arc minutes) of Saturn on May 23, 2015.  The planet’s equatorial angular diameter will be 19 arc seconds, its rings being 42 arc seconds across.

In our feature article below, “Saturn Through the Ages” — a departure from our usual technical take on the universe — we will be returning to times past to explore a piece of the puzzle that highlights our search for knowledge and meaning.

Saturn Through the Ages  

Throughout human history, we have looked to the light of the heavens to illuminate our role on Earth. Next time you are star gazing, consider all of the people throughout time and across the world who have reflected upon the same celestial bodies, conducting their nightly dance across our sky.

Our study of the celestial sphere has brought us understanding of physical and mathematical principles, models for society and perhaps fundamentally, a comforting sense of order. It is the human imagination however, and our quest to find a meaning behind this order, that led us to create a screenplay of the night sky. For millennia we have told our own tale through the guise of a heavenly cast of characters. Because celestial mythology is common throughout many cultures, these stories reveal our discoveries of the human condition.

In the upcoming month, many of us will be gazing at the planet Saturn in the northeastern sky. Perhaps due to a planet’s slow trek through our heavens, the stories we've told about Saturn often involve the passage of time and inevitable fate. We've expressed through Saturn both our appreciation for life and our fear of time's cruel and inescapable quality.

In ancient Mesopotamia, they prayed to Saturn as the Lord of Death, appealing to him thus:

“O Lord Saturn
whose name is august
whose power is widespread
whose spirit is sublime
O Lord Saturn
the cold, the dry, the dark, the harmful…
crafty sire who knowest all wiles
who are deceitful, sage and understanding
who causest prosperity and ruin
happy or unhappy is he whom thou makest such.”

In ancient Rome, Saturn was an agricultural god, a harvest deity. Controlling our fate through the success of our crop, he was celebrated in times of bounty and appealed to when times were hard. The Golden Age of Saturn, an ideal era of equality and abundance, was memorialized during the mid-winter festival of Saturnalia. A time of feasts and gifts from which we can trace rituals of modern day Christmas. During the celebration, a man chosen to represent the god was attentively fêted, only to be sacrificed on the final day of the festival. Try as we have to sway him however, we are all equally powerless before the forces personified by Saturn. 

In Hindu mythology, Saturn appears as the god Sani, holder of the secrets of fate. One could predict the future through use of a Saturn diagram, which represents the planet’s path through our skies. This god is so malevolent that a single glance from the evil-eyed deity burned off the head of the infant Ganesa, god of good fortune and prosperity. Associated with childhood disease, Sani demonstrates that not even a god’s luck can stand against the inevitability that Saturn represents.

Though we may wish it otherwise, nothing in our human existence remains static; nothing escapes the passage of time. Falcon-headed Horus, Saturnine god of the ancient Egyptians, succeeded his father Osiris when he was dethroned, marking the beginning of a new regime. As all change implies death of the old, we tell our tales of Saturn to reconcile ourselves to the necessity of welcoming the new. 

Cronos, Saturn-god of ancient Greece, whose name may originally have referred to his universal governance (from the verb kreno), became known as Father Time. Cronos not only overthrew and replaced his father, but consumed each of his own children at birth, much as time itself consumes all that it creates. Demonstrating the universality of this principle, Cronos himself was ultimately dethroned by his offspring, making way for a new era.

Through our creation of Saturn mythology, we attempt to explain our relationship to fate, time and death. Our ability to perceive these issues is fundamental to our very humanity. When next gazing at Saturn in the night sky, perhaps you will see not only a wonder of the cosmos, but also the history of humanity’s struggle to find meaning therein.

If you'd like to follow along with NASA's New Horizons Mission to Pluto and the Kuiper Belt, please download our FREE Pluto Safari app.  It is available for iOS and Android mobile devices. Simulate the July 14, 2015 flyby of Pluto, get regular mission news updates, and learn the history of Pluto.

Simulation Curriculum is the leader in space science curriculum solutions and the makers of Starry Night, SkySafari and Pluto Safari. Follow the mission to Pluto with us on Twitter @SkySafariAstro, Facebook and Instagram.