Updated periodically by Tom — BajaNightSky@gmail.com
Baja Night Sky #125 – Bright Iridium Flare, evening & morning planets, day-old Moon, last chance to see the Southern Cross before heading back north, Moon videos & more.
There are some things in the evening and early-morning sky you should see before you die or go back north. Let’s start with tonight’s sky (Monday, 4/15/2018). Go outside at 7:55 pm. In the west, just above the mountains behind El Sargento, the planet Venus is shining so brilliantly it can be found while dusk still lights the western sky. Do you also see the Moon? It’s about to set just three fingers below Venus at about 7 o’clock. At only a day old, it is just a thin crescent. Try using binoculars. It will be easier to spot Tuesday evening around 8:15 when it is just to the left of Venus in a darker sky.
Turn to the south and look for Sirius, brightest star in our night sky. The three stars in Orion’s belt point down towards Sirius. When you’ve found it, try finding Canopus, the second brightest star in the night sky, which is far below Sirius at 7 o’clock. Two fists to the left of Canopus is the False Cross lying on its side. As described below, when the Southern Cross in over the south point of the horizon it stands upright.
If the sky is now dark enough to see the Big Dipper back in the north, follow the arc of its handle down to Arcturus, 4th brightest star in the night sky. It is just rising over the southern end of Isla Cerralvo.
To see the Southern Cross and nearby globular cluster Omega Centauri, go out at 12:15 am when the Cross is standing upright just above the mountains in the south. For directions to finding Omega Centauri with binoculars, read Baja Night Sky #119 below but use the 12:15 am time.
Finally, for early morning risers, Mars (on the left) and Saturn are high in the south from 5 to 6am while even brighter Jupiter is higher in the SW. There will be another brilliant Iridium flare on Wednesday morning at 6:01:03 am just above and to the right of Saturn. After flaring, the satellite continues south and passes through the tail of the constellation Scorpio. The teakettle-shaped asterism of 8-9 bright stars below Saturn is part of the constellation Sagittarius. Can you spot it? It is tipped as though pouring boiling water onto the stinger of the scorpion. Between the spout and the stinger is the beautiful Ptolemy cluster of relatively young stars. It’s a fuzzy patch to the naked eye, but 100 or more sparkling stars through binoculars. The Butterfly Cluster is just above it. This region is near the black hole at the center of our Milky Way Galaxy.
Here are two interesting short videos about our nearest neighbor the moon.
Baja Night Sky #124 – Planets, flares, the Southern Cross, and the ISS
Monday evening Venus and Mercury will be low in the west after sunset. Venus is the brighter of the two. Mercury is just to the right of Venus. A narrow crescent Moon should be a fist above Venus. Here in El Sargento, both planets set behind the mountains to the west by about 7:10pm. The best time to spot them is between 6:40 and 7 pm just above the mountain peaks. Between 5 and 6 am Jupiter is high in the south while Mars is speeding towards an April 2nd conjunction with Saturn in the SE morning sky. Tonight there is a moderately bright Iridium flare at 7:47 pm between the bowl of the Big Dipper and the North Star. Tuesday night’s flare at 7:41 pm in the same location will be extremely bright. Tuesday is also the Spring Equinox. Sunrise will be exactly in the east, sunset exactly in the west.
Thursday evening the International Space Station (ISS) will rise in the SW around 7:31 pm, pass through Orion’s right knee, belt, and left shoulder (in El Sargento/La Ventana) before fading out of sight as it passes through the bowl of the Big Dipper.
If you still have never seen the famous Southern Cross and it’s nearby neighbor Omega Centauri, the cluster of several million stars, there is still time left before returning north where they stay below the southern horizon. But you will have to stay up late or get up early. Both can be found between 1 and 2 am just above the southern horizon. Read BNS #119 for directions.
Baja Night Sky #121 — Sirius, Canopus, Regulus, Southern Cross, Scorpius, Planets
February 12, 2018 – By 8 pm the constellation Orion is high in the south. You probably know that the three belt stars point down to Sirius, the brightest star in our night sky. Canopus, the second brightest star in the night sky has been up for about an hour. It is twinkling several colors far below Sirius at the 5 o’clock position. Turn around and face north and see if you can find the bowl of the Big Dipper rising over Cerralvo in the NE. By 9pm the Dipper’s handle is visible. Three stars make up the Dipper’s handle. The middle star at the bend in the handle is Mizar, the first star to ever be photographed. If you have good eyesight you should be able to see that Mizar is a double star. Look for its companion, Alcor, close by at the 7 o’clock position. Mizar and Alcor are themselves double stars but you need a spectroscope to detect their companions. You know the last two stars in the bowl point to Polaris, our current North Star. Use the same two stars to point in the opposite direction, east, and the first bright star you come to should be Regulus, the star at the bottom of the Sickle in the constellation Leo rising in the east.
Until next week, the only planets visible are in the early morning sky. Go out between 5 and 5:30 am and you will find Jupiter shining brightest high in the SE. Below Jupiter at the 8 o’clock position is reddish Mars. Just to the lower right of Mars is Antares, a word that means Rival of Mars. A line from Jupiter through Mars leads to bright Saturn just rising east of southeast. On Tuesday morning between 5:45 and 6 am a thin crescent rising moon will join the planets. Look for it just below Saturn. The entire constellation Scorpius, with Antares at the scorpion’s heart, is now high in the SE. With binoculars there are clusters to find just east of the stinger. First spot them with the naked eye, then with binoculars. Below Saturn is the famous Teakettle asterism in the constellation Sagittarius. The handle is on the eastern edge, the top just below Saturn, and the spout near the stinger of Scorpius. Surrounding the Teakettle are many globular and open clusters waiting for you to discover with binoculars or telescope.
Several people have asked what the best time is to find the Southern Cross and the giant globular cluster Omega Centauri made up of some 5 million stars. Since every star rises 4 minutes earlier each evening, those 4 minutes quickly add up to two hours every month (30 days). So you have to be up between 2:45 and 4:45 am to catch them both now. Around 3:45 am is when the Cross sits just above the mountains to the south. Check the Baja Night Sky #119 below for how to find Omega Centauri with binoculars.
Baja Night Sky #120 — The Stars and Myths of the Constellation Orion.
Note: We will have a few hours of dark moonless evenings on February 2-6, and 18. Moonless morning before sunrise occur on February 14-27.
Friday, February 2, 2018 —The brightest constellation in the night sky, Orion, is easy to find during February evenings high in the southeastern sky. It is one of the six constellations lying on the Winter Circle. The red giant Betelgeuse (upper left) along with the bright blue-white star Rigel (lower right), and the three equally spaced stars forming Orion’s belt make the hunter constellation easy to identify. But there is a lot more going on in this constellation than meets the eye.
Stars are born, live anywhere from a few million years to billions of years, and die, some with a whimper and others with a bang. And it’s all happening in Orion. Stars are being born now in the famous Orion Nebula. With binoculars or a telescope, you can see the greenish hued cloud of gas & dust surrounding some of the middle stars of Orion’s sword which hangs beneath his belt. This giant cloud of mostly hydrogen, with heavier elements such as silver and gold that were created by earlier supernovae, is collapsing under the force of gravity. This has already produced the pressure and heat necessary to ignite thermonuclear fusion in denser pockets of gas, releasing massive amounts of energy as described by Einstein’s famous equation E = mc^2. The Trapezium is a group of newly born stars at the center of the Nebula. Just last year, the Hubble Space Telescope found more than 17 new brown and red dwarfs in the nebula. Brown dwarfs are bigger than planets but so small they never warm up enough to go nuclear. Red dwarfs have ignited but because of their size are difficult to detect. They are probably the most numerous stars in our galaxy.
Rigel represents Orion’s left foot (but from our perspective at the lower right). It’s living a fast life and has already turned all its hydrogen into helium. At only 8 million years, it is younger than some of our earliest human ancestors. Its small size (compared to Betelgeuse) leaves uncertain as to whether it will explode as a supernova or collapse into a super-dense Earth-size neutron star. Betelgeuse, on the other hand, could go supernova at any time. It’s low on fuel. When gravity overcomes the outward pressure of fusion energy, the giant star will collapse in seconds creating a super fusion bomb that will create the heavier elements and blow them all back out into space for inhabitants of some future Earth to use in jewelry making. I hope I’m around when it happens. No worry. It’s too far away to endanger our planet..
You may be familiar with Orion in Greek mythology. The warrior bragged he could kill all the animals on Earth. Gaia sent the scorpion to sting Orion’s heel and kill him. Zeus rescued Orion and placed him in the sky. But fearing the scorpion, Orion only rises in the east after Scorpius has set in the west.
For the Pericu Indians of the Cape Region, the three stars in the belt of Orion represented the stones their God Niparaya used to descend from heaven onto Cerro Puerto, the highest peak to the west of El Sargento. From there, Niparaya created humans and all the plants and animals they would need to survive in happiness. Incidentally, the stars in the belt are only 5-6million years old. There are older rocks in your back yard.
Orion’s belt has other uses for star gazers. It points down to Sirius, brightest star in the night sky, and up to Aldebraran, the eye of Taurus the bull. Spend an evening with Orion. Explore the region with binoculars. Two sides of the Winter Hexagon are formed by lines connecting Aldebraran to Rigel and Rigel to Sirius. Can you trace out the other four sides? See BNS # 117 below.
There is still time on moonless mornings to see the Southern Cross and the giant globular cluster Omega Centauri. But since the stars rise 4 minutes earlier each night, this month you will need to be up between 4 and 5 am for best viewing. See BNS #119.
Click here for more info on Betelgeuse and a link to info on Rigel, the brightest star in the constellation Orion. Here is an interesting article on the Gould Belt that is responsible for many of Orion’s young stars.
Baja Night Sky #119 – Finding the Southern Cross and its neighbors.
Monday, January 15, 2018 – The Southern Cross is visible here in the Cape Region from about January 15 to June 15. The best time to look is when it is highest, within half an hour or so on either side of due south. It is very low on the horizon, the bottom star of the cross only a finger or two above the mountains. When directly in the south, the Cross stands more or less upright. There is a false cross low in the south 4 hours earlier that is on its side. As we orbit the sun, we see the same stars 4 minutes earlier each night. In a month that adds up to two hours earlier. So since we can see the Cross at 5:45 am January 15, in 4 months it will be visible 4 x 2 = 8 hours earlier at around 9:45 pm on May 15. That is why the local Mexicans call the Southern Cross La Cruz de Mayo.
To find the constellation’s 4 brighter stars, go outside by 5:30 am. You will need a dark location with a building or other object blocking the street lights of the town. By 5:45, two bright stars on the SSE southern horizon point west a fist+ at the bright star at the top of the cross. The left crossbar star is also relatively bright. The other two stars of the Cross are dimmer. The pointer stars are (on the left) Rigil Kentaurus (Alpha Centauri), the closest star system to us, and Hadar. Alpha Centauri is the 3rd brightest star in the night sky and less than 4 light years away.
To find Omega Centauri, the largest of 150 globular clusters orbiting the Milky Way, start at the right pointer star Hadar. About 4 fingers above Hadar is the next naked eye star called Burdin. Extend a line from Hadar through Burdin and extend it about 3 finger widths. Using averted vision, scan this region watching for a faint round cloud. Use binoculars for a more impressive view. At 15,600 light years, the cluster, even with 5 million stars, is too distant to make out individual stars through binoculars.
Globular clusters are compact collections of very old stars just outside the Milky Way. Open clusters are groups of young stars recently formed from giant molecular gas clouds inside the Milky Way. The Jewel Box is a sparkling open cluster of young stars of varying colors. Start at Becrux, the left crossbar star of the Cross. Scan down to the 7 o’clock position about 1 finger width. Just below the Jewel Box there is a large dark area of no stars caused by a giant cloud of dust blocking star light. The cloud is known as the Coal Sack.
Magellan and other explorers sailing around South America were encouraged when they spotted the Southern Cross whose long axis points to the south celestial pole. The constellation was memorialized in the Crosby, Stills and Nash song of the same name in the following four lines:
When you see the Southern Cross for the first time
understand now why you came this way
‘Cause the truth you might be runnin’ from is so small
But it’s as big as the promise, the promise of a comin’ day.
New Moon at 7:17pm Tuesday. Try to spot the 23-hour-old crescent moon on Wednesday evening before it sets around 6pm.
Direct questions, complaints, or suggestions to Tom at BajaNightSky@gmail.com
Baja Night Sky #118 — Conjunctions, The Double Cluster
Friday, January 12, 2018 —
The wandering planets have always fascinated humans. Trying to explain their movements led to the argument Copernicus made for a Sun-centered solar system that revolutionized our world view. Once their movements could be explained and predicted, they lost their mystery and power over our imagination. But they are still fun to watch. Right now, Jupiter is many times brighter than its nearby companion Mars. But keep an eye on Mars. As we catch up with it on our orbit just inside the red planet’s orbit, it will grow brighter until it becomes twice as bright as Jupiter at opposition in July. In the meantime, as Mercury disappears into the glare of the rising Sun, Saturn will move higher and closer to Mars and the two will be in a side-by-side conjunction on April 1.
During a spur-of-the-moment star gazing session with my Ranger friend the other evening, we were looking overhead at the M-shaped constellation of Cassiopeia. Suddenly he remarked that he could see a cluster of many faint stars just above the last two stars on the right side of Cassiopeia’s M. He was using averted vision, the more sensitive periphery of the retina rather than the color-sensitive center we use during the day and for fine detail work. He had spotted the famous Double Cluster in Perseus, two adjacent clusters of young stars, more than 300 all together. They were first cataloged in 130BC by the astronomer Hipparcos who must have also had superior vision. They are spectacular through binoculars or on low power through a telescope. And a great naked-eye test for your night vision. At around 7:00-7:30 pm for the next couple of weeks, you can look for the clusters more or less above the North Star about 5-6 fists above the horizon.
And if you are out any clear evening soon, find the easily identified constellation of Orion in the east. Its belt of three equally spaced stars points down to Sirius, brightest star in the night sky. Starting with Sirius and going clockwise, can you name the bright stars in the Winter Circle (BNS #117)? Oh, happy birthday J. Tom at BajaNightSky@gmail.com
Baja Night Sky #117
Monday, January 8, 2018 – The Winter Circle and Star Names
With moonless evenings now, the brightest stars of winter form the famous Winter Circle, a giant oblong hexagon of bright stars now in the eastern sky. Best viewing is from 8 to 10 pm. Start with Sirius, brightest star in the night sky, rising low in the SE. Sirius is close at only 8.6 light years. Move clockwise to Procyon, 8th brightest star in the night sky, due east and the same altitude as Sirius (from 8-9pm). Slightly higher moving clockwise are Pollux & Castor at the next corner of the hexagon. Pollux is the 17th brightest star. High above Pollux & Castor is Capella, 6th brightest star. Now swing back south (to your right) to the giant red star Aldebaran, 13th brightest star and eye of Taurus the Bull constellation. The famous Pleiades star cluster is about a fist+ above Aldebaran. People with good eyesight can make out 8-10 of the clusters brightest stars. Continue right and down to Rigel, one foot of Orion and 7th brightest in the sky. Rigel is a young blue-white star. To Rigel’s left is the giant red star, and shoulder of Orion, the 9th brightest star Betelgeuse. It’s big and living a fast life. Once it has burned up it hydrogen fuel it will explode into a nova and be the brightest star in the sky for a short time. At a distance of 500 light years, the explosion should not affect Earth. From Rigel down to Sirius completes the trip around the Winter Circle. See that bright star rising in the SE? That’s Canopus, 2nd brightest star in the night sky. Since it is far from the plane of the bright planets,the ecliptic, it is used by spacecraft for navigation purposes.
With 100 billion or more stars in our galaxy, with naked eye we can only see about 10,000 of the closest and brightest ones during a year’s trip around the Sun. While astronomers have assigned coded letter and numeral designations to several million stars, only 313 of the brightest or most interesting actually have names. Most are ancient Arabic, Greek or Latin such as the ones named above. But 86 were recently added to the named stars by the International Astronomical Union. All of these have names from other cultures such as Chinese, Polynesian, and Aztec. Tom at BajaNightSky@gmail.com
Baja Night Sky #116
Saturday, January 6, 2018 – Get your flare fix this weekend. Most flares will end by mid-year as the older Iridium satellites are taken out of orbit and replaced with new non-flaring ones. Tonight’s flare (Saturday) will be brighter than any star in the sky. Look for it beginning at 6:43:09 pm (10 seconds later and not as bright in Los Barriles), 30 degrees (3 fists at arm’s length) above the SSW horizon (one fist west of due south). Sunday evenings flare, more like one of the brighter stars, will be in the same location at 6:37pm. Monday evening will provide one of the brightest flares ever at 6:34:17 pm at the same location as the others. The US Naval Observatory provides MST (Baja Sur time) to the second at http://www.usno.navy.mil/USNO/time/display-clocks/simpletime.
In the early-morning eastern sky (between 5:30 and 6am) Jupiter has been the brightest object high in the SE. Red Mars has been just above it and moving closer each morning. Sunday morning they will be in conjunction (closest approach) at about half a moon width from each other. Look for Mars at the 5 o’clock position from Jupiter. If you have binoculars, look for Jupiter’s 4 largest and closest moons, much closer to Jupiter than Mars. Callisto and Ganymede are in conjunction at the 1 o’clock position from Jupiter. Even closer to Jupiter, Europa and Io (also in conjunction with each other) are at the 7 o’clock position. Mercury is still low on the horizon but will soon enter the glare of the rising Sun.
If the sky is still dark on the southern horizon, try to find the Southern Cross standing just above the mountains. More about this interesting constellation when dark skies come with the new moon in a week.
Baja Night Sky #115
Jan 1, 2018 – It was from ancient folklore about the night sky that the science of astronomy developed. Supermoons, minimoons, and blue moons, though more recent folklore, are part of the same tradition. Blue moons aren’t blue unless there is some unusual atmospheric condition such as smoke with ice crystals. The definition most used currently for a blue moon is the second full moon in the same month. It happens twice this year in both January and March. It won’t happen twice again until 2037 (when I hope to see it at age 100). A supermoon is simply a full moon that occurs within at least 10% of the moon’s closest approach to Earth on its elliptical orbit, a point called perigee. This can happen three months in a row with the middle supermoon usually being the largest. A minimoon is a full moon that occurs within 10% of it farthest distance from Earth called apogee. The January 31st full Moon will be a blue supermoon that will be completely eclipsed by Earth’s shadow at 6:30:57am just before it sets in the west. While the Earth blocks sunlight during an eclipse of the moon, sunlight passing through Earth’s atmosphere is bent enough to cast a reddish hue onto the moon. This is often called a blood moon. So on the 31st we will have a blue super total eclipse blood moon as it sets in the west. With nothing to compare it to, a supermoon may not appear any larger than normal even though the area (and therefore brightness) of the moon appears up to 28% greater. To see how a supermoon compares to a minimoon click here .
Baja Night Sky #114
Dec 27, 2017 – Catch a rare double flare tonight at 7:24:28 and 7:26:18 pm if partly cloudy skies cooperate. The first satellite will flare like a brighter star a fist east of due south and two fists above the horizon. The second flare, in the same location, should be brighter than any star in the sky. It comes from a spare satellite 110 seconds behind the first.
Baja Night Sky #113
Dec 20, 2017 – Sunset is around 5:37 pm. Recall that if there are mountains to your west sunset will occur around 15 minutes earlier; the same for moonset times. So sunset Wednesday evening is 5:37/5:22 pm depending on your view to the west. Find a dark location shielded from outdoor lights by 6:50pm. While your eyes are adjusting to the dark, look for the 5th brightest star, Vega, setting in the NW. Altair to its upper left and Deneb above form the Summer Triangle. Capella, the 6th brightest star, is in the NE over Isla Cerralvo. The constellations Orion and Taurus are rising in the east. Betelguese (reddish) and Rigel (blue-white) are the two brightest stars in Orion. Orion’s three belt stars points up to red Aldebaran in V-shaped Taurus the Bull. It’s the 13th brightest star in the night sky. Can you pick out 6 or 7 of the stars that make up the Pleiades a fist or so above Aldebran? They also form the logo you see on Subaru autos. Polaris, the North Star and 48th brightest star, is 2+ fists above the northern horizon.
The 2 ½ day old New Moon sets about 7:54/7:40 pm. Look for the Old Moon in the arms of the crescent New Moon. The Old Moon is illuminated by sunlight reflected back from Earth. It’s a beautiful sight that many people have never seen.
Check the Baja Night Sky #110 for how to spot our sister galaxy Andromeda. Just change the best observation time to 6:50 – 7:10 pm when it will be almost directly above the North Star.
Baja Night Sky — #112: Space Stations and Andromeda Galaxy
Dec 18, 2017 – Sunset this week is around 5:36 pm. However, if there are mountains to your west sunset will occur around 15 minutes earlier; the same for moonset times. So sunset Monday evening is 5:36/5:21 pm depending on your view to the west. Find a dark location shielded from outdoor lights (remember to leave your outdoor lights off) by 6pm. While your eyes are adjusting to the dark, look for the 5th brightest star, Vega, setting in the NW. Capella, the 6th brightest star, is just rising in the NE over Isla Cerralvo. The bright stars in the constellations of Orion and Taurus (blue-white Rigel in Orion and red Aldebaran above in Taurus) are just rising in the east. Polaris, the North Star and 48th brightest, is 2+ fists above the northern horizon.
The 6 hour old New Moon sets at 6:15/6:00 but has too thin a crescent to spot. On Tuesday and Wednesday evenings try to spot the Old Moon in the arms of the crescent New Moon. The Old Moon is illuminated by sunlight reflected back from Earth. It’s a beautiful sight that many people have never seen. Moonset times are 7:04/6:49 and 7:54/7:40 pm respectively. Begin looking 15 minutes earlier.
The International Space Station (ISS) will make a bright pass over the East Cape Monday evening. Look for it rising in the NW around 6:19, passing near Vega at 6:20, through Cygnus the Swan at 6:21, high in the SW under the Great Square of Pegasus at 6:22, and slowly fading from sight in the SE from 6:24 to 6:25.
At the same time, a dim Iridium Satellite will rise in the north around 6:20 and provide a brilliant flare at 6:25:43 pm about 3 fists above the SSW (a bit south of southwest) horizon. Flares last about 4-8 seconds as sunlight is briefly reflected from the satellite. (In the Los Barriles region, the flare will occur Tuesday evening at 6:19:44 in the same location as the satellite makes another pass).To top things off, Tiangong 2, China’s experimental space station, will rise in the SW a 6:43 pm, be overhead around6:46, and set in the NE about 6:49.
Check the Baja Night Sky #110 for how to spot our sister galaxy Andromeda. Just change the time to 7-7:20 pm when it will be almost directly above the North Star.
Baja Night Sky — #111: The Geminid Meteor Shower
Dec 11, 2017 — The Gaminid Meteor Shower begins Dec 13 (Wed) night and reaches its peak in the hours after midnight. http://earthsky.org/astronomy-essentials/everything-you-need-to-know-geminid-meteor-shower, Tom at BajaNightSky@gmail.com
Baja Night Sky — #110: Finding the Great Andromeda Galaxy.
Dec 8, 2017 — With later moonrises this weekend, early dark skies provide a chance to spot the most distant object possible with the naked eye at 2.5 million light years. Around 7:30 find a dark location shielded from outdoor lights and wait for your eyes to adapt to the dark. The Andromeda Galaxy is our nearest neighbor outside our home galaxy, the Milky Way. Light from Andromeda begins as photons created by nuclear fission at the centers of the galaxy’s 200 billion+ stars, then travel for millions of years to reach Earth. Search from 7:40 to 8:00. First find the North Star. It’s not the brightest star in the sky, but easy to find standing alone 2.5 fists above the north horizon. Look three fists above Polaris for Cassiopeia, the constellation whose 5 brightest stars form an M. The second and highest star from the left is Shedar. A line from Polaris up to Shedar and extended another 1 ½ fists ends at Andromeda. Look for a fuzzy patch of light the size of the moon. It helps to use averted vision, turning your eyes slightly to one side so that photons from Andromeda strike the night vision part of your retina. Binoculars make the galaxy easier to find. Don’t give up. It may take a few minutes to collect enough photons for your brain to put Andromeda’s image together.
Baja Night Sky #109 — Five Planets
Nov 20, 2017 — The five brightest planets are hanging around near the sun this month. After sunset tonight, look for Mercury and Saturn low in the SW between 6 and 6:30pm. Mercury is the brighter but difficult to spot less than a fist above the horizon. Look for Saturn just above it next to a slim two-day-old crescent moon. Venus and Jupiter rise in the east just before dawn. Look for them between 6 and 6:30am. Venus, nearest to the horizon, is the brighter of the two, brighter than any star in the night sky. Mars is two fists above Jupiter.
Baja Night Sky #108
Friday, April 14, 2017 — Several sky observers asked if they had found one of Jupiter’s 63 or so moons, or a star. How do you distinguish a moon of Jupiter from a remote star whose light is passing near Jupiter? When you look at Jupiter rising in the east, its 4 largest moons will be found above, below, crossing, or hiding behind Jupiter. Their position will change hourly. Sometimes all four are on the same side. At times one or more will be very close to Jupiter, making it difficult to distinguish them from the giant planet using binoculars. Nearby stars, like the one at the 7 o’clock position around 9pm, do not change position over a few hours or days.
That very bright morning star rising around 5:30am is Venus. It’s got a very long day. It takes 243 Earth days for Venus to turn once on its axis to complete a Venusian day.
Baja Night Sky #107
April 7, 2017 — Sunday, April 9, the Don Diablo Trail Run begins near La Paz at 7am. The Sun will rise around 7:05am. Mountains to the northeast will delay sunrise at the start line by about 20 minutes. Weather forecast mostly sunny with a high near 88F. The sun will set behind the mountains in El Sargento about 7:15pm. Twilight and a bright moon will illuminate the early evening.
The bright star rising in the east before sunrise is Venus. It moved westward between Earth and the Sun during the past two weeks going from evening to morning star. Mercury, closest planet to the Sun, is still an evening star. It is difficult to find since it is only visible for a short time during twilight. Use binoculars between 7 and 7:15pm to find it just above the mountains to the west. In a few days, it will disappear into the Sun’s glare before joining Venus in the east at month’s end as a second morning star. Mars is above Mercury a fist and a half for a few more evenings.
Jupiter will appear its largest and brightest of the year this evening. Its orbit brings it closest to Earthtonight when it is opposite the Sun from our planet. It will rise at sunset, be overhead at midnight, and set at sunrise. Now is the best time until May 9, 2018 to see how many of its four large Galilean moons you can see using binoculars or a telescope.