Seeing Stars with James Wooten: Jupiter is Shining Bright

This star map shows the Houston sky at 10 pm CDT on August 1, 9 pm CDT on August 15, and dusk on August 31.  To use the map, put the direction you are facing at the bottom. The Summer Triangle is high overhead.  This consists of the brightest stars in Cygnus, Lyra, and Aquila.  Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left.  From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest.  Mars begins to pass under Saturn in the south at dusk.  The Great Square of Pegasus rises in the east, heralding the coming autumn.

This star map shows the Houston sky at 10 pm CDT on August 1, 9 pm CDT on August 15, and dusk on August 31. To use the map, put the direction you are facing at the bottom.
The Summer Triangle is high overhead. This consists of the brightest stars in Cygnus, Lyra, and Aquila. Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left. From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest. Mars begins to pass under Saturn in the south at dusk. The Great Square of Pegasus rises in the east, heralding the coming autumn.

Jupiter is low in the west at dusk; this is the last month to see it in the evening sky until March 2017. It outshines all stars we ever see at night, so you can’t miss it even as it sets in twilight.

Venus begins to re-emerge into the evening sky this month. How soon can you spot it low in the evening twilight? Towards the end of the month, watch Venus approach Jupiter; they are only 0.07 degrees apart on August 27. On that night you must observe right after sunset to catch that pair, as they set before twilight ends.

Mars and Saturn are now in the south southwest at dusk.

Mars continues to fade each night as Earth leaves it farther and farther behind. Also, it moves faster than Saturn against the background stars, so you can watch Mars overtake Saturn this month. Today, Mars is to the right and is much brighter. By August 23-24, however, Mars will pass between Saturn and the bright star under it, Antares in Scorpius. By the end of the month, Mars is to the left of Saturn.

The Big Dipper is above the North Star, with its handle pointing up. From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are in the west at dusk.

Antares, brightest star of Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to its left. Saturn is right above Antares. The Summer Triangle is almost overhead. The stars of summer are here. Meanwhile, the Great Square of Pegasus rises in the east at dusk, and is fully risen by month’s end. Autumn is on the way.

Moon Phases

Moon Phases in August 2016:

New Aug. 2, 3:45 p.m.

1st Quarter Aug. 10, 1:21 p.m.

Full Aug. 18, 4:27 a.m.

Last Quarter Aug. 24, 10:41 p.m.

As of Jul 19, 2016, Brazos Bend State Park is all dried out from the floods of April and May and back open to the public. Come see us Saturday nights at the George Observatory! On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer.
Clear Skies!

Seeing Stars with James Wooten: Mars and Jupiter Shine Bright

This star map shows the Houston sky at 10 pm CDT on July 1, 9 pm CDT on July 15, and dusk on July 31.  To use the map, put the direction you are facing at the bottom. The Summer Triangle is high in the east.  This consists of the brightest stars in Cygnus, Lyra, and Aquila.  Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left.  Leo, the Lion, sets in the west with Jupiter.  From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest.  Mars and Saturn remain in the south at dusk.

This star map shows the Houston sky at 10 pm CDT on July 1, 9 pm CDT on July 15, and dusk on July 31. To use the map, put the direction you are facing at the bottom.
The Summer Triangle is high in the east. This consists of the brightest stars in Cygnus, Lyra, and Aquila. Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to his left. Leo, the Lion, sets in the west with Jupiter. From the Big Dipper’s handle, ‘arc to Arcturus’ and ‘speed on to Spica’ in the southwest. Mars and Saturn remain in the south at dusk.

Jupiter is now in the west at dusk. It outshines all stars we ever see at night, so you can’t miss it.

Mars and Saturn are now in the south at dusk. As you watch them, Mars is to the right and is much brighter.

Although Mars continues to fade each night as Earth leaves it farther and farther behind, this month Mars still outshines all of the stars and even rivals Jupiter in brightness! By the end of the month, Mars begins to approach Saturn.

Venus is lost in the Sun’s glare and out of sight all month.

The Big Dipper is above the North Star, with its handle pointing up. From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are in the west at dusk. Leo, the Lion, is also in the west at dusk.

Antares, brightest star of Scorpius, the Scorpion, is in the south, with the ‘teapot’ of Sagittarius to its left. Saturn is right above Antares. The Summer Triangle has fully risen in the east. The stars of summer are here.

Moon Phases
Moon Phases in July 2016:

New July 4, 6:01 a.m.

1st Quarter July 11, 7:52 p.m.

Full July 19, 5:57 p.m.

Last Quarter July 26, 6:00 p.m.

At 11:00 am on Monday, July 4, Earth is at aphelion. This means that on this date Earth is as far from the Sun as it will get this year. But all of us can feel how hot and sticky it is outside now, compared to January, when Earth was at its closest. This is because the Earth’s orbit is almost a circle; the difference between closest and farthest distance from the Sun is small. Indeed, Earth is only 1.6% farther than average from the Sun on July 4. The effect of Earth’s 23.5 degree tilt easily dominates the tiny effect of Earth’s varying distance from the Sun.

Also on July 4, the Juno spacecraft enters Jupiter orbit. For just over a year and a half, Juno will execute 37 orbits of Jupiter before a controlled orbit into Jupiter in February 2018. The spacecraft is designed to explore the inner composition of Jupiter, giving more information about what’s far beneath the cloud layers we see.

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. As of now, however, George is closed while Brazos Bend State park dries out from yet another round of floods on the Brazos River. The park could reopen as early as July 12.

Clear Skies!

James G. Wooten
Planetarium Astronomer
Houston Museum of Natural Science

Seeing Stars with James Wooten: Exciting Rare Mercury Transit Next Monday!

May Starmap

Jupiter is now high in the south at dusk. It outshines all stars we ever see at night, so you can’t miss it.

Mars and Saturn become late evening objects this month. Tonight, May 2, Mars rises in the southeast at 9:48 p.m. while Saturn comes up soon afterwards, at 10:24 p.m. By May 15, though, both planets rise during twilight, and on Memorial Day both are in the southeastern sky as soon as it gets dark. Mars and Saturn are still above the distinctive pattern of Scorpius, the scorpion. As you watch them rise, Mars is to the upper right and is much brighter.

In fact, this month, Mars outshines all of the stars and even rivals Jupiter in brightness! That’s because on May 22, Earth passes between the Sun and Mars. That alignment is called ‘opposition’ because it puts Mars opposite the Sun in our sky, making Mars visible literally all night long. It also makes Mars much brighter than normal in the sky, since we’re as close to it as we’ll ever get until Earth overtakes Mars again in 2018. Saturn comes to opposition June 3.

Venus is lost in the Sun’s glare and out of sight all month.

A swath of brilliant winter stars sets in the west at dusk. Orion, the Hunter, is still visible in the west as May begins. His two dogs, represented by Sirius and Procyon, are to his left.  Gemini, the Twins, are above Orion. The Big Dipper is above the North Star, with its handle pointing to the right. From that handle, you can ‘arc to Arcturus’ and then ‘speed on to Spica’; those stars are high in the east and in the south, respectively, at dusk. Leo, the Lion, passes almost overhead at dusk.

As Orion and his dogs set, look for Antares, the brightest star in Scorpius, the Scorpion, to rise in the southeast. Saturn and Mars will rise with the Scorpion’s head, above Antares. At the same time, Vega, brightest star of the Summer Triangle, appears low in the northeast. These stars remind us that summer is on the way.

Moon Phases

Moon Phases in May 2016:

New: May 6, 2:30 p.m.

First Quarter: May 13, 12:02 p.m.

Full: May 21, 4:14 p.m.

Last Quarter: May 29, 7:12 a.m.

Mercury Transit:

On Monday, May 9, 2016, Mercury overtakes Earth on its much faster orbit. This time, though, when Mercury passes Earth, the alignment is almost exact, such that Mercury appears in silhouette against the sun’s disk. This event is known as a transit of Mercury. Keep in mind that the planets are almost, but not exactly, in the same plane. Indeed, Mercury’s orbit is the most inclined — tilted up to 7 degrees from Earth’s orbital plane. That’s why Mercury does not usually transit the sun when it overtakes Earth. Monday’s event is therefore rare and special, occurring only 14 times in the 21st century (the next one occurs Nov. 11, 2019).

Transit_of_Mercury_May_9_2016_path_across_sun

Thus, weather permitting, the Houston Museum of Natural Science has arranged for volunteers from local astronomy clubs to set up solar telescopes outside our museum’s main entrance, near the sundial, to show you the transit. Mercury, already in the sun’s disk by sunrise in Houston, takes until 1:42 p.m. to cross to the other side of the sun’s disk. If skies cooperate, we’ll observe the transit from 10 a.m. until 1:42 p.m. on Monday, May 9. If there are sunspots on the sun’s disk while Mercury is there, Mercury will stand out because its disk is fully round and because Mercury moves noticeably across the sun’s disk during the hours we’re watching.

We will observe the sun (and Mercury in silhouette) through telescopes with filters especially designed to filter the sun safely, and by projecting the sun’s image onto a screen. These are the only two ways to observe the Sun safely. Please do not try to observe the sun directly or through an unfiltered telescope, as this will lead to permanent eye damage or blindness. Our common sense tells us this because we always avert our eyes when we accidentally turn towards the Sun. When something cool happens on the sun, some of us try to override our common sense, and there is no reason to do so. Come observe safely with us.

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. As of now, George is closed which Brazos Bend State Park dries out from last month’s floods, and is scheduled to reopen May 10. If you’re there, listen for my announcement. 

Seeing Stars with James Wooten: Five planets at dawn, leap day this February!

Star Map

Jupiter is now a late evening object, rising in the east. It rises by 9 p.m. on Feb. 1, and by Feb. 29 it comes up just before 7 p.m., which is during evening twilight. Jupiter comes to opposition on March 8, which is when Earth aligns with Jupiter and the Sun. That is why Jupiter is up all night long in late February and early March.

As dawn approaches this month, Jupiter will still be visible, this time high in the west.  Meanwhile, the four other visible planets will have risen as well. That’s right, February 2016  features all five naked-eye planets at dawn!

Venus is in the southeast at dawn. You can’t miss it, as Venus outshines all the stars we see at night, and in fact outshines everything but the Sun and the Moon.

Mars is in the south at dawn. Noticeably reddish in tint, Mars continues to brighten each day until its opposition next spring. 

Saturn is in the south southeast at dawn, above the distinctive pattern of Scorpius, the scorpion. Mars slowly approaches Saturn this month.

Mercury is the biggest challenge to find. This month, though, Mercury is very close to Venus and to its left. Thus, once you find Venus, the brightest dot to its left is Mercury. 

Mercury is the first planet to leave the gathering as it heads back towards the Sun late this month. The cutoff date of Feb. 20 is somewhat arbitrary, though. It’s better to watch the sky and, using Venus as your guide, see for yourself when is the last day you can still see Mercury before losing it the Sun’s glare. The next to leave is Jupiter, which shifts into the evening sky after opposition. 

Taurus, the Bull, is high in the south. Look for the Pleiades star cluster above reddish Aldebaran. Dazzling Orion, the Hunter, takes center stage on winter evenings.  Surrounding Orion are the brilliant stars of winter. Orion’s belt points down to Sirius, the Dog Star, which outshines all other stars we ever see at night. The Little Dog Star, Procyon, rises with Sirius and is level with Orion’s shoulder as they swing towards the south. To the upper left of Orion’s shoulder is Gemini, the Twins.

Under Sirius and low to the southern horizon this month is a star that most Americans never get to see—Canopus. Representing the bottom (keel) of the legendary ship Argo, Canopus is the second brightest star ever visible at night. Thus, it is clearly noticeable along the southern horizon on February and March evenings. However, you must be south of 37 degrees north to see Canopus rise. (This is the line that divides Utah, Colorado, and Kansas from Arizona, New Mexico, and Oklahoma.)

The sky we see depends on our latitude as well as on the time of night and time of year.  From any given location in our hemisphere, there is an area of the sky around the North Star in which stars never set (circumpolar stars), and an equivalent area around the South Celestial Pole in which stars never rise. The closer you are to the pole, the larger these areas are. The closer you get to the equator, the fewer circumpolar stars there are, but there are also fewer stars that never rise for you. At the equator, no stars are either circumpolar or never visible; all of them rise and set as Earth turns. 

That’s why, down here in south Texas, the Big Dipper sets for a while although it’s always up for most Americans. On the other hand, Canopus, too far south to rise for most Americans, rises for us.

Moon Phases

Moon Phases in February 2016:

Last Quarter: Jan. 31, 9:28 p.m.

New: Feb. 8, 8:39 a.m.

First Quarter: Feb. 15, 1:46 a.m.

Full: Feb. 22, 12:20 p.m.

(February is so short that last quarter Moons occur on Jan. 31 and March 1, but not in February). 

The New Moon of Feb. 8 is the second New Moon after the winter solstice. Accordingly, it marks Chinese New Year. Welcome to the Year of the Monkey!

Monday, Feb. 29, is leap day. This day exists because our normal year of 365 days is too short. The true length of one Earth orbit around the Sun is 365 days and almost 6 hours.  No one wants to begin a year in the middle of a day, however. Therefore, we let the error add up over four years, until it becomes 24 hours, or one whole day, then add that day back to the calendar. Thus, February 29 occurs every four years. 

Almost 6 hours?  Well, alright, the difference between our orbit and our year is actually 5 hours, 49 minutes, and 16 seconds. That makes our system a very slight overcorrection.  To prevent that from adding up, we’ll skip leap day in 2100, 2200, and 2300. 

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. If you’re there, listen for my announcement. 

Clear Skies!