Go stargazing! July edition

Jupiter
Creative Commons License photo credit: KingArthur10

Jupiter is up all night long this month. At about 3 am on July 9, the Earth will pass between the Sun and Jupiter. This alignment is called opposition because it puts the Sun and Jupiter on opposite sides of the Earth.

Being opposite the Sun in our sky, Jupiter rises at sunset and sets at sunrise; it is up literally all night long the night of July 8-9 and up virtually all night for the whole month. Jupiter outshines everything else in the night sky this month unless the moon is present.

Jupiter is easy to find this July; it is low in the southeast at dusk or low in the southwest at dawn.

Mars and Saturn are also visable this month. Look west at dusk to find stars in the shape of a backwards question mark.  These form the mane of the constellation Leo the lion.  The point under the question mark is Regulus.

Saturn is to Regulus’ upper left.  On July 1, Mars is to the lower right of Saturn, near Regulus.  Saturn is the brighter of the two; Mars continues to fade each day as Earth pulls away from it. Watch each night as Mars approaches Saturn and passes it on July 10. By the end of July, Mars will be up and to the left of Saturn, and both will be lower to the horizon at dusk. The Moon is near Mars and Saturn on July 6th. Venus is lost in the Sun’s glare, and will remain out of sight through the end of the summer.

International Space Station & Half-Moon & Saturn & Regulus
Creative Commons License photo credit: scyllarides

The brightest star in the sky tonight is Arcturus, which you can find by extending the arc of the Big Dipper’s handle (arc to Arcturus).  Arcturus, the fourth brightest star we see at night, is the brightest star left since the top three are not visible in Houston in July.

The Big Dipper happens to be to the upper left of the North Star at dusk this month.

Scorpius, the Scorpion, is in the southeast at dusk.  Sagittarius, the Archer, known for its teapot asterism, is to Scorpius’ left.

 In the east, look for the enormous Summer Triangle, consisting of the stars Deneb, Vega, and Altair. This triangle is up all night long in July, hence its name.

Of the three Summer Triangle stars, Vega is the brightest (in fact, 5th brightest overall and 2nd only to Arcturus on July nights). However, Deneb actually puts out far more light, despite the fact that Deneb is about 3000 light years away, compared to 25 light years for Vega.  Star brightness depends not only on intrinsic power, but on distance.

Moon Phases in July 2008:

New July 2, 9:19 pm
1st Quarter July 9, 11:34 pm
Full July 18, 2:59 1m
Last Quarter July 25, 1:42 pm
Full Moon
Creative Commons License photo credit: Andréia

At about 3 am on Friday, July 4, 2008, the Earth is at aphelion (greatest distance from the Sun). We were closest to the Sun about six months ago, on January 2.  This serves as an excellent reminder that it’s the Earth’s tilt on its axis, and not its varying distance from the Sun, which causes our seasons.

Astronomers define the average Earth-Sun distance (about 93 million miles) as one astronomical unit, or AU. On July 4, we will have moved out to 1.016 AU, while on January 2 we were at 0.983 AU. This is not enough of a difference to affect how much warmth comes our way; it’s going to stay hot and sticky for a while.

Go stargazing! June edition

Say Aaaaaah
Creative Commons License photo credit: exfordy

Mars and Saturn are high in the west at dusk this month.  Look west at dusk to find stars in the shape of a backwards question mark.  These form the mane of Leo, the lion.  The ‘point’ under the question mark is Regulus, a star of similar brightness. Saturn is to Regulus’ upper left.  Mars is to the lower right of Saturn, easily outshining the very dim stars around it.  Saturn is the brighter of the two; Mars continues to fade each day as Earth pulls away from it. 

This month, you can watch Mars dramatically close in on Saturn.  Mars begins the month about 20 degrees to the lower right of Saturn. (Your fist, held at arm’s length, blocks about 10 degrees.) By month’s end, Mars will be next to Regulus, less than 5 degrees from Saturn.

The Moon is near Mars on June 7, and near Regulus and Saturn on June 8. 

Jupiter is in the predawn sky this month, in the southeast at dawn. It outshines everything else there unless the Moon is present.  It is now also a late evening object, rising by 11 p.m. on June 1 and just after dusk on June 30.  Next month, it will be up all night long. 

Venus is lost in the Sun’s glare, and will remain out of sight through the end of the summer.  On June 8, Venus is directly behind the Sun, an alignment called ‘superior conjunction’

 

Rho Oph Cloud Star Forming Region
Creative Commons License photo credit: Image Editor

The brightest star in the sky tonight is Arcturus, which you can find by extending the arc of the Big Dipper’s handle (‘arc to Arcturus’).  Arcturus, the fourth brightest star we see at night, is the brightest star left since the top three are not visible in Houston in June. 

The Big Dipper happens to be near its highest point above the North Star at dusk this month.  In the east, look for the enormous Summer Triangle, consisting of the stars Deneb, Vega, and Altair.  This triangle is up all night long in June and July, hence its name. 

scorpion
Creative Commons License photo credit: uhuru1701

Scorpius, the Scorpion, is in the southeast at dusk.  Sagittarius, the Archer, known for its ‘teapot’ asterism, rises just after dusk on June 1, but is up by nightfall on June 30.

 

Moon Phases in June 2008:

New    June 3, 2:23 pm
1st Quarter  June 10, 10:02 am
Full   June 18, 12:30 pm
Last Quarter  June 26, 7:10 pm

 

At 6:59 pm on Friday, June 20, the Sun is overhead on the Tropic of Cancer, the most northerly latitude at which the Sun can be overhead.  This is the moment of the summer solstice, the official start of summer.  For anyone in the Northern Hemisphere, June 20 has more daylight than any other day this year.  In the Southern Hemisphere, June 20 marks the winter solstice and is the shortest day of the year. 

However, the earliest sunrise occurs ten days before the solstice, on June 10, while the latest sunset is on the evening of June 30.  Since most of us sleep through sunrise and witness sunset, the days will seem to lengthen until the end of month although they begin getting (slightly) shorter after June 20.

For the best viewing conditions, get as far away from the city as you can – and visit us again to let us know what you see.

On Sunday, May 25, the Phoenix Mars Lander arrived safely on Mars.  Larger than the Mars rovers (which are still actively doing science on the Red Planet), Phoenix itself is not a rover; it will remain in the polar region where it landed.  Its mission is twofold: to study the history of water on Mars, and to determine if there is a habitable zone where the polar ice meets the soil.   You can follow the mission at its main website.

 

Go Stargazing! May Edition

Venus

Creative Commons License photo credit: fdecomite

Overall, the May evening sky marks a transition.  Brilliant winter stars (including Sirius) are leaving the evening sky, while the stars of summer are only beginning to peek over the eastern horizon. 

At dusk this month, the plane of the Milky Way roughly coincides with the horizon.  We are therefore looking up out of the Milky Way plane, where there are fewer bright stars.  One bright star high in the sky tonight is Arcturus, which you can find by extending the arc of the Big Dipper’s handle (‘arc to Arcturus’). 

Arcturus, the fourth brightest star we see at night, will be the brightest star left once we can no longer see Sirius.  The Big Dipper happens to be at its highest above the North Star at dusk this month.Mercury makes a brief appearance in the evening sky this month. Look for it in the west at dusk, right over the point of sunset.

Mars continues to fade as Earth pulls away from it.  To see Mars, look high in the sky to the west at dusk to the upper left of the ‘twin’ stars of Gemini. Mars’ position among the stars changes quite noticeably on a nightly basis. 

Saturn is high in the sky towards the south at dusk this month.  Look to the south at dusk, almost overhead, to find stars in the shape of a backwards question mark.  These form the mane of Leo, the lion.  The ‘point’ under the question mark is Regulus, a star of similar brightness. Saturn is to Regulus’ left.  

Jupiter is in the predawn sky this month, located in the south at dawn. It outshines everything else there unless the Moon is present. 

Venus is lost in the Sun’s glare, and will remain out of sight through the end of the summer.

Little Beehive - Messier 41

Creative Commons License photo credit: 3D King

When do the Dog Days of Summer begin?  Find out for yourself by noting when the last day in May is that you can still see Sirius, the Dog Star.  As May opens, Sirius is easy to find; it outshines all other stars we see at night and is the brightest thing in the southwest at dusk.  However, Sirius appears lower and lower to the horizon each night this month.  As May comes to a close, Sirius sets deeper and deeper in twilight and finally becomes invisible by month’s end.  Ancient Egyptians believed that Sirius, as the brightest star in the night sky, would reinforce the Sun’s heat if it were up during the daytime.  Thus, the time of year when Sirius is not visible at night (and therefore up only in daytime) became known as the ‘Dog Days’.

 

The bird and the moon II

Creative Commons License photo credit: *L*u*z*a*

Moon Phases in May 2008:

New May 5, 7:18 am
1st Quarter May 11, 10:46 pm
Full May 19, 9:11 pm
Last Quarter May 27, 9:57 pm

For the best viewing conditions, get as far away from the city as you can – and visit us again to let us know what you see.