Starry Night College Textbook - Horry-Georgetown Instructions

To resolve the error when submitting an assignment in Starry Night College Textbook, we have new instructions to login at https://learn.simcur.com. Before following these instructions, ensure that you have the new login password sent earlier by email. Please contact your instructor if you do not have it.

Update: Video walkthrough is available here: https://youtu.be/Tyr7PX4oOhU

Please follow the personalized instructions below to login to Starry Night moving forward.

Step 1.  Sign Into Starry Night

  • Go to https://learn.simcur.com

  • Click on “Sign In”.

  • Sign Into Starry Night using your school email (ends with @hgtc.edu).
    Note: if you don’t see the window below, select “Sign Out of All Accounts” and try again.

  • Click “Continue”.

Step 2. Choose a System

  • In the “Choose a System” window, select the “Canvas” option, NOT Brightspace. If you select Brightspace, you will not be able to submit your assignments.

Step 3. Login in with your student email and new password.

  • A new window pops up.

  • Enter your student email and the custom password that was emailed to you earlier.

  • Click “Login” and then “Authorize” in the new window that opens.

  • You are now logged in.

Notes:

  1. Your previous assignments up to Feb 6. will not be visible.  However, your instructor has your grades already for all assignments before this date.

  2. You can still sign in to Brightspace to view previous assignments by selecting the “Brightspace” option in the Choose a System window. However, after Feb 6 you should select the Canvas option to do and submit your work.


Exploring The Earth: Hudson's Bay And The Last Ice Age

(EXPLORING THE EARTH will be a regular series of columns that will examine various aspects of Earth Science through the lens of The Layered Earth software.  This first feature in this series examines the affect of the last ice age on Hudson Bay and how The Layered Earth software can be used to illustrate several unique features of this geological event.)

Hudson Bay, in north-eastern Canada, is one of the most prominent physical features of North America.  Today it is the second largest bay in the world, after the Bay of Bengal, east of India. 

The physical location of Hudson Bay in North America.

Sixteen thousand years ago, however, Hudson Bay lay crushed beneath an ice sheet that was 3 km (1.9 miles) thick. 

The extent of the ice sheet covering North America 16,000 years ago.

Layered Earth Software Users: To view the ice sheet covering much of North America 16,000 years ago:

  • Click on the Layers button in the bottom left corner of the screen.
  • Navigate through the following subdirectories:
  • CLIMATE → ICE COVER (insert a checkmark inside this box by clicking with your mouse inside the box)→ MAPS
  • Click the radio button for 16,000 YEARS AGO.
  • (Note: Clicking other radio buttons in this section will allow you to explore how the extent of the ice sheet has varied over time. Go ahead and explore!)
  • Click the Reset button in the tool bar (upper part of screen) in order to return to the default Earth view when you have finished exploring in this section.

This ice sheet was so heavy that it actually depressed the Earth’s crust underneath it.  Hudson Bay only finally became free of ice sometime between 8,000 – 9,000 years ago.  The removal of this immense ice burden allowed the depressed crust under Hudson Bay to slowly rebound.  This rebounding continues to this day.  Evidence of a depressed crust under Hudson Bay can still be seen today in gravity anomaly maps of the area.  The entire Hudson Bay area still exhibits a negative gravity anomaly; this means that the measured value of g, the acceleration due to gravity, is less than it should be as a result of the depressed crust.

The negative gravity anomaly in the Hudson Bay area.

Layered Earth Software Users: To view the gravity anomaly data set:

  • Click on the Layers button in the bottom left corner of the screen.
  • Navigate through the following subdirectories:
  • GEOPHYSICS → GRAVITATIONAL ANOMALY (insert a checkmark inside this box)→ MAPS

The gravity anomaly data will now appear on the globe, however, a clear view of the data is obstructed by the underlying satellite view of North America. To enhance your view of the gravity anomaly data:

  • Go to the SATELLITE IMAGERY subdirectory. Click on the checkmark in the box beside the subdirectory name. This removes the checkmark in this subdirectory and removes the satellite imagery data as active data.
  • Go to TOPOGRAPHY AND BATHYMETRY → COASTLINE AND BORDERS (insert a checkmark inside this box)
  • Click the radio button for N. Amer. States and Provinces. You should now have a clear view of the gravity anomaly data along with state/provincial outlines in North America in order to give a clearer geographical context.
  • (Small points representing stars are still visible in the background at this point. If you want to remove these then remove the checkmark in the box beside the ATMOSPHERE AND STARS subdirectory.)
  • Click the Reset button in the tool bar (upper part of screen) in order to return to the default Earth view when you have finished exploring in this section.

Clear physical evidence of the rebounding of the Earth’s crust (known as isostatic rebound) can be found by carefully examining the shore of Hudson Bay.  Once such area can be located at 56.390N, 87.950W.  You can rotate the globe manually until you locate these coordinates, or you could use the Search function

This unusual view of the Hudson Bay coastline can be found at 56.390N, 87.950W.

You should now be able to see an unusual series on lines on the land surface that are parallel to the coast.  What you are looking at is a series of old beach levels that mark the location of previous shorelines on Hudson Bay.  They are now inland because of the isostatic rebound of the crust under Hudson Bay.

Explore up and down the coast of Hudson Bay to discover other areas that nicely illustrate these previous shoreline levels.  Another particularly nice example of old shorelines can be found at 58.430N, 93.100W. 

Reference Files

Ready access to all of the views and data sets that have been mentioned in this article are available if you own The Layered Earth Software.  Each file (after it has been downloaded) can be viewed by clicking File/Open in the upper menu bar, and then following the path to its location.

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.

Never stop improving! Starry Night 7.4.1 update is now live!

More than a year and a half into the release of Starry Night 7 we are still working furiously to bring fresh improvements and features to Starry Night. Developers see software the same way that artists see their creations - always in need of improvement.

 

7.4.1 Release Notes

New Features:

- Added a preference to support drawing selection labels as plain text (as in V6), instead of textured tags.
- Added Drag-Drop support for dropping SNFs onto the Starry Night sky to open.
- (Enthusiast) Added "Night Vision" mode.
- Added back Ambient Audio.
- Exported Observing Lists now include J2000 positions.
- Remembers your last open/save folder locations and defaults to these on File > Open/Save.


Fixed Bugs / Improvements:

- Fixed setting panoramas in locations that have pre-defined associations (e.g. Toronto, Detroit.)
- All log entries now show up in search results (was missing some with parentheses in their name.)
- Fixed Custom horizon images and editing.
- Fixed date formatting display (OSX).
- Fixed Meteor Shower radiant drawing. (Was too dim on OSX).
- Fixed movie creation of very large movies (OSX).
- Fixed trackpad click and drags (OSX).
- Fixed Constellation search results.
- Planet elongation correctly reported. (Was always showing zero.)
- Equipment List saved immediately on dialog close. (No loss if crash.)
- Satellites no longer use advanced magnitude calculations when not valid (i.e. far above Earth.)

 

The best part of making software is knowing that the changes you make affect so many people who use your creation regularly. The improvements made to satisfy your need for perfection benefit many!

So fire up your Starry Night 7 and tell us what you think about the latest changes!

Falling Leaves And Autumn Skies

The autumn sky shows the transition from the summer Milky Way, through the “watery” constellations of autumn, to the bright stars of winter. Credit: Starry Night software.

Autumn is the favorite season for many skywatchers. You can get your last look at summer stars and, if you stay up late, your first look at winter stars. Best of all, it gets dark earlier and the night temperatures are still comfortable.

Our graphic this week shows a panorama of the sky looking south around 8 p.m., just after the sky becomes fully dark. After the change to standard time this weekend, this will be the view at around 7 p.m.

Looking towards the west, at the right in the graphic, you can see the familiar constellations of summer. Sagittarius and the core of the Milky Way Galaxy are setting in the southwest, while the summer triangle: Deneb, Vega, and Altair, shines overhead.

It’s not too late to revisit some of the popular summer objects: double stars Albireo and Epsilon Lyrae, the globular clusters in Hercules and Ophiuchus, the Ring Nebula in Lyra, and the bright nebulae and clusters of Sagittarius.

Looking south, the upside down triangle of Capricornus rides high. Its rightmost star, Algedi, is a naked-eye double. Above Capricornus, just to the left of Altair, is the tiny constellation Delphinus, the dolphin, one of the few constellations that actually looks like its name. It’s worth exploring the region between Altair and Albireo, where you will find two of the finest deep sky objects: Brocchi’s Cluster, popularly called “the coat hanger,” and the Dumbbell Nebula, one of the largest and brightest planetary nebulae.

Many of the constellations in the autumn sky have watery associations. These include Capricornus (the sea goat), Delphinus (the dolphin), Aquarius (the water bearer), Pisces (the fish, plural), Piscis Australis (the southern fish, singular), and Cetus (the whale). Most of these are lacking in bright stars, with the exception of Pisces Australis which contains the first magnitude star Fomalhaut, the first star to have one of its planets directly imaged by the Hubble Space Telescope.

Although Aquarius is dim in terms of stars, it contains a number of fine deep sky objects, including the globular cluster Messier 2, and two fine planetary nebulae, the small bright Saturn Nebula snd the huge Helix Nebula. The latter is probably the planetary nebula closest to the sun, about 700 light years distant, and as a result is very large in size, almost as large as the moon. Because of its large angular size, its light is spread out over a wide area, making it very hard to see. You will need a narrow band filter on your telescope to spot it. 

Off to the east, the Square of Pegasus dominates the sky. This consists of three stars in Pegasus with the fourth corner of the square being marked by Alpheratz, the brightest star in the constellation Andromeda, which trails away to the northeast.

Right in the upper left corner of the graphic are the two largest and brightest galaxies in our neighborhood, the Andromeda Galaxy and the Triangulum Galaxy. These are located symmetrically on either side of the second pair of stars eastward from Alpheratz in Andromeda.

The Andromeda Galaxy (to the north) is large and bright. If you live in a city, you will need binoculars to see it, but sharp-eyed observers in the country, including myself, have spotted it with their unaided eyes. The Triangulum Galaxy is almost as large, but nowhere near as bright as Andromeda. It is best seen in small binoculars. Oddly, it is very hard to see in the narrow field of a telescope because its dim light is spread across such a large area.

Finally, in the northeast you can see the first of the winter stars, the bright star Capella in Auriga and the brilliant Pleiades Cluster in Taurus. Soon Orion will arrive in the east, in the words of Robert Frost:

            You know Orion always comes up sideways.

            Throwing a leg up over our fence of mountains,

            And rising on his hands, he looks in on me…

 Stay up until midnight, and you will see him, too.

 

Spot The Bright Asteroid Vesta

The next two weeks are an excellent opportunity to spot the brightest of the asteroids, Vesta.

In the first six years of the 19th century, astronomers discovered four new members of the solar system. All four were small objects moving in orbits between the orbits of Mars and Jupiter. Initially they were called planets, but by mid century, enough new objects had been found in this area that they were given a category of their own, much as Pluto was reclassified from a planet to a dwarf planet. They were called asteroids because all were so small that they looked just like stars in the telescopes of the day. Now there are tens of thousands of known asteroids.

Vesta is the brightest of all the asteroids, ranging between magnitudes 5 and 8, and one of the largest, measuring 318 miles (512 km) across. It reached 6th magnitude at opposition on September 29, meaning that it could just barely be seen by someone with perfect eyesight at a perfectly dark site.

The rest of us have to make do with binoculars. Heres how to find it.

A wide angle view of the autumn constellations, showing the position of the asteroid Vesta in Cetus. Credit: Starry Night software.

The first chart shows its overall position among the constellations of autumn. The two left-hand stars of the Square of Pegasus, Alpheratz and Algenib, point southward across the circlet of Pisces to the constellation Cetus, the Whale. Look for a large triangle formed by Eta and Iota Ceti and Deneb Kaitos. The last is easy to spot because, although only second magnitude, it is by far the brightest star in this rather dim part of the sky. Eta and Iota are both magnitude 3.5, so quite a lot dimmer than Deneb Kaitos.

A close up of the westernmost stars of Cetus, showing the position of the asteroid Vesta over the next two weeks. Credit: Starry Night software.

The second chart shows these three stars in detail, and the path of Vesta over the next two weeks. The end of Vestas path with the label is its position on Wednesday, September 30, and the points on the trail to the right show its position each night after that.

Vesta should be quite easy to spot, since it is about two magnitudes brighter than any of the stars along its track. Just to be sure, make a simple plot of the stars in its vicinity, and then check again a night or two later. The star that has moved is certain to be Vesta.

Vesta is now one of the best known objects in the solar system because it had the NASA spacecraft Dawn orbiting it for over a year (July 2011September 2012). This is a great chance for you to see it with your own eyes.

The Super-Blood-Moon Lunar Eclipse

This Sunday evening, 9/27, stargazers will see a rare supermoon lunar eclipse. If you miss it, the next one isn't until 2033! What makes this event so special?

A Full Moon

First, the moon will be full, as it always must be for a lunar eclipse to occur. This is a special full moon, all on its own, because this is the harvest moon. Traditionally, this designation goes to the full moon closest to the autumnal equinox. In two years out of three, the harvest moon appears in September, but every third year it occurs in October.
 
At this time of year, corn, pumpkins, squash, beans, and wild rice—the chief Native American staples—are ready for gathering; and at the peak of the harvest, farmers could work into the night by the light of this full moon.
 
Most of the year, the moon rises an average of 50 minutes later each night, but for the few nights around the harvest moon, the moon seems to rise at nearly the same time each night: just 25 to 30 minutes later across the United States, and only 10 to 20 minutes later for much of Canada and Europe.

A Supermoon

Secondly, the full moon will be at its closest to Earth in all of 2015, what is known to astronomers as a perigee moon. In recent years this has become known as a “supermoon.” Perigee (meaning “closest to Earth”) occurs at 10 p.m. EDT, the moon being a mere 222,374 miles (357,877 km) from Earth.
 
In fact, the human eye can’t detect the 5 percent difference in size between the moon at perigee and the moon at apogee (farthest from Earth), but everyone who looks at the moon Sunday night will swear it looks bigger than usual. Partly that is because, when seen low on the horizon, the human eye and brain combine to create an optical illusion known as the moon illusion, whereby the moon (and other objects) seen close to the horizon seem larger than when seen overhead.
 
The moon is the same size regardless of how low or high it is above the horizon. To prove this to yourself, cut out a circle just big enough to block the moon at arm's length and use it to see for yourself that its size stays the same as it rises in the sky.
 
The only noticeable effect of a perigee moon is that the ocean tides will be a bit higher than usual for the day of full moon and the next three days.

A Total Lunar Eclipse

The third, and most important part of this special event, is that we will have a total eclipse of the moon. At most full moons, the sun, Earth and moon line up approximately, but because of the tilt of the moon’s orbit, the moon passes above or below the Earth’s shadow, and avoids being eclipsed.

At certain points in the moon’s orbit, sun, Earth, and moon line up exactly, and the Earth’s shadow falls across the face of the moon, and we have a lunar eclipse. This is what will happen Sunday night.

The moon’s shadow has two parts: a darker inner part called the umbra, and a lighter outer part called the penumbra. This is because the sun is not a point source of light, so its light leaks around the edge of the Earth, and results in an unsharp shadow. In passing through the Earth’s atmosphere, the light turns red or orange, so that the light that actually reaches the moon is tinted by thousands of sunsets and sunrises all around the periphery of the Earth.


One result of these multiple sunrises and sunsets is that the moon during an eclipse is often tinted red, which is the origin of the idea of a lunar eclipse being a “blood moon.” It isn’t a far stretch of the human imagination to turn this “blood moon” into a portent of disaster.

A lot has been made in the media of this eclipse being the fourth event in a foursome of total eclipses known as a “lunar tetrad.” There really is nothing unusual about four lunar eclipses in two years, since we usually average at least two lunar eclipses every year, though not all are total.
 
In fact, there was no tetrad of total eclipses at all, because the last lunar eclipse, on April 4, was not really a total eclipse. According to the usual way of calculating eclipses, the moon spent only 4 1/2 minutes in the umbral shadow, but recently this calculation method has been corrected, resulting in the April eclipse failing to be total at all.
 
This Sunday’s lunar eclipse is a true total eclipse, with the moon being in the umbra for a full hour and twenty-two minutes.

When To See It

Observers in eastern and central regions of North America will get to see the whole eclipse; those further west will see the moon rise already partially eclipsed. Observers in Europe and Africa will see the eclipse before dawn on Monday, September 28.
 
This brings up the question of dates and times, which often causes confusion. Even a usually reliable source like Canada’s Weather Network, got the date of this eclipse wrong.
 
Officially, mid-eclipse occurs on September 28 at 02:47 Universal Time, which is the same as Greenwich Mean Time (but NOT British Summer Time). Subtracting 4 hours, this places mid-eclipse in the Eastern Daylight Time zone at 10:47 p.m. on the evening of September 27; the date changes at midnight. So be sure you look for the eclipse on Sunday evening. If you wait until Monday evening, you will be a day late.

Here are the important times in Eastern Daylight Time; if you’re using CDT, MDT, or PDT, the times will be earlier by 1, 2, or 3 hours.
 
EDT
08:11:46  Moon enters penumbra
09:07:12  Moon enters outer edge of umbra
10:11:11  Moon completely in umbra
10:47:09  Mid-eclipse
11:23:07  Moon begins to emerge from umbra
12:27:06  Moon completely out of umbra
01:22:33  Moon leaves penumbra
 
As always, we look forward to your pictures of this beautiful event.

The Third of Four Eclipses In 2015 - September 13

The third of four eclipses in 2015 will occur this Sunday, September 13. It will be a partial eclipse of the sun, and unfortunately it will be visible only from southern Africa, the Indian Ocean, and parts of Antarctica.

On Sunday morning, September 13, there will be a partial eclipse of the sun, visible in southern Africa, the Indian Ocean, and parts of Antarctica. Here it is seen from Cape Town, South Africa, where it will be at its maximum. Credit: Starry Night software.

The best view of this eclipse from an urban area will be from Cape Town, South Africa, where a maximum of 30 percent of the sun will be covered by the moon.

The eclipse begins in Cape Town just as the sun and moon are rising at 6:49 a.m. local time. Early risers will see a tiny bite out of the sun. It reaches its maximum at 7:43 a.m. By 8:50 a.m. the eclipse will be over.

This eclipse will be visible throughout South Africa, and also in southern parts of Madagascar, Mozambique, Zambia, and Zimbabwe. It will also be visible over a wide area of the Indian Ocean, and Antarctica (if you happen to be a penguin).

The best way to observe a partial solar eclipse is with a filter specifically designed for observing the sun, sold by stores specializing in telescopes. Safe eclipse shades are often widely available prior to an eclipse. A number 14 welders glass also works well, and is available from specialized welding shops. The ordinary number 12 welders glass sold in hardware stores does not provide adequate protection.

If you dont have a proper solar filter, you can view the partially eclipsed sun with a pinhole camera by punching a hole about a millimeter in diameter in a piece of cardboard. Natural pinholes created by leaves on trees or reflections from a buildings windows will also work.

Under NO circumstances look directly at the sun, even with sunglasses, as you can quickly cause permanent damage to your eyes. If a small magnifying glass can light a fire in seconds, think what will happen to the retina of your eye by staring at the sun.

As always, we welcome your pictures of the partially eclipsed sun; a solar filter on your camera will be essential. The sensor in your camera is just as easily damaged by the direct sun as your eyes. Try to get a landmark or tree in the foreground to give a sense of scale.

Sky Events For September 2015

Moon Phases

Saturday, September 5, 5:54 a.m. EDT

Last Quarter Moon

The Last Quarter Moon rises around 11:30 p.m. and sets around 3 p.m. It is most easily seen just after sunrise in the southern sky.

Sunday, September 13, 2:41 a.m. EDT

New Moon

The Moon is not visible on the date of New Moon because it is too close to the Sun, but can be seen low in the East as a narrow crescent a morning or two before, just before sunrise. It is visible low in the West an evening or two after New Moon.

Monday, September 21, 4:59 a.m. EDT

First Quarter Moon

The First Quarter Moon rises around 1:30 p.m. and sets around midnight. It dominates the evening sky.

Sunday, September 27, 10:51 p.m. EDT

Full Moon

The September Full Moon is known as the Harvest Moon or Full Corn Moon. It rises around sunset and sets around sunrise; this is the only night in the month when the Moon is in the sky all night long. The rest of the month, the Moon spends at least some time in the daytime sky.

Observing Highlights

Neptune at opposition

Tuesday, September 1, midnight

Neptune will be directly opposite the Sun in the sky, and visible all night. It is located in Aquarius but is too faint to be seen with the unaided eye. Use binoculars and a star chart from Starry Night.

Mercury at greatest elongation east

Thursday and Friday, September 3 and 4, dusk

Mercury will be well placed in the evening sky for observers in the southern hemisphere, less so for observers in the north.

Aldebaran and the Moon

Friday/Saturday, September 4/5, near midnight EDT

Observers on the eastern part of North America with low eastern horizons may be able to see the Moon occult the first magnitude star Aldebaran just after moonrise (around midnight, but check for local times). Observers in Europe will see it just before sunrise on the 5th.

Zodiacal light

Friday, September 11–Thursday, September 24, before dawn

The best time in the year to see the dim glow of the zodiacal light in the pre-dawn eastern sky, the light reflected from millions of interplanetary particles. It lies along the ecliptic (shown in green).

Partial solar eclipse

Sunday, September 13

This eclipse will be visible from southern Africa, Antarctica, and the oceans in between. Seen here is the maximum eclipse in Cape Town, South Africa.

Equinox

Wednesday, September 23, 4:21 a.m. EDT

The Sun crosses the celestial equator moving southward, causing the days to grow shorter in the northern hemisphere and longer in the southern hemisphere.

Lunar trio

Sunday, September 27, evening

There will be a triple treat for observers in eastern North America as sun, Earth, and moon align: a total lunar eclipse, the moon at its closest, and a full moon, all in one evening. At 8:12 p.m. EDT, the lunar eclipse will begin with the first faint lunar shadow creeping onto the moon. At 9:48, the moon reaches an extreme perigee, the closest it will get to Earth in all of 2015: 221,753 miles (356,877 km). Total phase of the eclipse will begin at 10:11 p.m. and mid eclipse will be at 10:47. At 10:51 it will be the instant of full moon, the largest full moon in 2015. At 11:23, the total phase of the eclipse will end, and at 1:23 a.m. the last of the moon’s shadow will leave the moon. In western North America, the moon will already be in eclipse when the moon rises. Observers in South America, Europe, and Africa will also see most of this eclipse. The illustration shows the moon just entering the umbral shadow of Earth at 9:12 p.m. EDT.

Vesta at opposition

Monday, September 28, 11 p.m. EDT

The brightest asteroid Vesta will be directly opposite the Sun and visible all night in Cetus. At magnitude 6.2, it will be right at the limit of naked-eye visibility, but easily spotted with binoculars.

Planets

Mercury is well placed in the evening twilight for the first half of the month. This apparition is more favorable for observers in the Southern Hemisphere.

Venus is now a bright object in the pre-dawn sky, reaching maximum brightness of magnitude –4.8 on the 21st.

Mars is low in the eastern twilight, moving eastward through Cancer into Leo.

Jupiter reappears in the eastern pre-dawn sky in the middle of the month..

Saturn is low in the southwest mid-evening sky, and sets in late evening.

Uranus rises in mid-evening in Pisces, nearing opposition on October 12. 

Neptune is in opposition on the 1st, visible all night in the constellation Aquarius.

Look For Mercury This Week

Mercury reaches its greatest elongation east of the sun this week on Friday, September 4. 

On Friday, September 4, Mercury will be at its greatest elongation east of the Sun. Credit: Starry Night software.

Here we see it as we might from space, say on the International Space Station or the Hubble Space Telescope. The green line marks the ecliptic, the path the sun appears to follow over the year. Most of the planets also appear to revolve in this same plane.

The red line is Mercurys orbit, which you can see is tilted quite a bit compared to the ecliptic. Of all the planets, Mercurys 7 degree tilt is the most extreme. The small orange dot marks Mercurys position on Friday, as far east of the sun as it can go.

How will Mercury look to us here on the surface of the Earth? It very much depends on where you are located.

As seen from Europe and North America, the ecliptic makes a shallow angle with the horizon, so Mercury is not well placed. Credit: Starry Night software.

This view of Mercury is how it will appear to me from my location close to Toronto, Canada at sunset. Everyone at a similar latitude across southern Canada, the northern United States, and most of Europe and Asia will see something very similar.

Because of the Earths current position in its orbit around the sun, the ecliptic makes a very shallow angle with the western horizon as seen from the northern hemisphere. So even though Mercury is as far west of the sun as it can get, at this time of year it ends up very close to the horizon around sunset, the best time to look for it. To make matters worse, because of its orbits tilt, Mercury is quite far south of the ecliptic at this time. As a result Mercury is barely 7 degrees above the horizon at sunset.

The situation in the southern hemisphere, here seen from southern Australia, is very different. The ecliptic makes a very steep angle with the horizon, and Mercury is south of the ecliptic, so Mercury is much higher above the horizon at sunset, 26 degrees in fact.

As seen from Australia and South Africa, the ecliptic makes a steep angle with the horizon, so Mercury is very well placed. Credit: Starry Night software.

As a result, spotting Mercury from the northern hemisphere will be a major challenge this week, but the lucky people in the southern hemisphere will have a fine view.

This situation reverses in the spring, when northerners get a fine view of Mercury at dusk, and southerners are out of luck. It also reverses when Mercury is at elongation on the western side of the sun. That is why every year we publish a table showing which elongations of Mercury will be favorable or unfavorable, depending on which hemisphere you view it from.

All in all, even though it is very bright, Mercury is probably the most challenging planet to view. You have to be in the right place at the right time.

Mercury viewed through a telescope is a disappointment. The most you will see is a tiny disk, which goes through phases similar to Venus and the moon. But it is a great satisfaction to most stargazers to say that they have actually seen it at all.

See The Supermoon On Saturday

Youll probably be hearing a lot about a super moon for the next few months. This is not a term that astronomers use, but here are some facts about what will actually be happening.

Full moon is when the sun, Earth, and moon line up with the Earth in the middle. As seen from the surface of the Earth, the moon is fully illuminated. Because it is exactly opposite the sun in the sky, the moon rises in the east just as the sun sets in the west and, roughly 12 hours later, sets in the west just as the sun is rising in the east.

Because the Earth is constantly revolving around the sun and the moon is constantly revolving around the Earth, full moon is an instantaneous event, occurring when the moon is exactly opposite the sun. This week this happens at 2:35 p.m. EDT on Saturday, August 29. 

Full moon occurs this month at 2:35 p.m. EDT on Saturday, August 29. Credit: Starry Night software.

A minute earlier, the moons phase is waxing gibbous, and a minute later it is waning gibbous.

Each full moon occurs roughly 29.53 days after the previous full moon. Roughly because the moons orbit around the Earth is not a perfect circle, but instead is elliptical in shape. The exact time of full moon varies a little bit from month to month.

The most important result of the moons elliptical orbit is that sometimes the moon is closer to the Earth, and sometimes farther away. The time when it is nearest is called perigee and the time when it is farthest is called apogee.

What we are most interested in is perigee, the date and time when the moon is closest to Earth. This month perigee occurs on Sunday, August 30, at 11 a.m. EDT, about 18 hours after full moon. At that time, the moon will be 222,631 miles (358,290 km) away from Earth.

The moon will be closest to the Earth, called perigee, the next morning at 11 a.m. Credit: Starry Night software.

Notice how less than a days change in position makes it clear that the moon is no longer full: you can see that it is lit more from the left side.

Events like full moon and perigee occur at exactly the same time when viewed from anywhere on Earth, even though the local time on the clock may look different. This month both full moon and perigee occur when it is daytime in North America, and the moon is below the horizon. The best time to see the full moon at perigee will be on Saturday evening, August 29. The moon will be a few hours past full, and perigee will be a few hours in the future, but thats the closest we can get this month.

The important thing for astronomers is that the perigee distance is less than 360,000 kilometers. When the moon gets this close, its most important effect on the Earth, the ocean tides, gets stronger. On the day of perigee and the three days following, we will have larger tides than usual.

Looking ahead to next month, full moon will fall on Sunday, September 27 at 10:51 p.m. EDT, and perigee just 51 minutes earlier at 10 p.m. This perigee will be the closest in 2015, 221,753 miles (356,877 km). The result will be the largest full moon of the year, and even larger high tides. Notice that both events happen in the evening when the moon will be well placed in the sky.

The full moon of September is traditionally called the harvest moon, because it rises around sunset on several successive nights, giving farmers extra light in the evening to bring in their harvest.

The September full moon will also pass through the Earths shadow, a total eclipse of the moon, visible on the evening of September 27 in North and South America, and the morning of September 28 in Europe and Africa.

When the moon is close to full, we can see the strong contrast between its grey plains and white mountainous regions, which some people see as the man in the moon and others see as a rabbit.

With the naked eye or a small binocular, you can easily see the three main dark plains on the upper half of the moon, which bear the fanciful names of the Oceanus Procellarum (Ocean of Storms), Mare Serenitatis (Sea of Serenity), and Mare Imbrium (Sea of Rains). These were named before we knew that there were no open bodies of water on the moon, and no atmosphere to cause storms or rains. Look also for the brightest crater on the moon, Tycho, with its beautiful system of rays, cause by material expelled when it was caused by the impact of an asteroid millions of years ago.