A Starlink Satellite Swarm

   Growing up during the 1960s I often spent many evenings outside with my father watching for satellites to pass over where we lived. I learned how to differentiate between an airplane and a satellite by watching the object as it approached the horizon. An airplane lights may be followed all the way to the horizon while the reflected sunlight from a satellite appears and disappears above the horizon as the satellite moves out of and then back into the Earth’s shadow. This was the early days of satellite technology and the time of communication satellites like Telstar, as well as satellites we presumed were Russian spy satellites.
      In today’s world satellites and space exploration have lost some of the public awareness and popularity. However there are many easy to see satellites including the International Space Station, the Hubble Space Telescope, a variety of communication satellites, and most recently the Starlink Satellites.
   The Starlink is a satellite built by SpaceX for the intention of providing satellite Internet access. Initially the focus will be on satellites providing Internet connection for much of North America but with the eventual launching of around 12,000 satellites the entire globe may have satellite Internet access.
   Currently the Starlink satellites appear in groups of 50 or so and look like a string of bright pearls stretched across the sky. Watch the video below of the Starlink Satellites passing over England.
   The Starlink Satellites move rapidly compared to the ISS and the group last night, in my pictures, were around 2nd magnitude or brighter. The group moved out the northwest past the Big Dipper and Arcturus toward the southeast. The satellites appear as streaks of light because the pictures were time exposures lasting 5 or 6 seconds each.

Use the Heavens Above web site for maps and times for viewing the ISS, Starlink and other satellites.
Use the NASA ISS Sightings web site for specific viewing times and directions for your location.
Use this web site, What the Astronauts See Right Now, for a simulated view from the ISS looking down at the Earth’s surface it is orbiting over.


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

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2017 Quadrantid Meteor Shower

   The annual Quadrantid Meteor Shower reaches its peak Tuesday morning January 3rd officially at 15 UT (10 am CST). The Quadrantids are one of the best meteor showers of the year but does not get much attention possibly because it’s winter in the northern hemisphere, and this area of the sky is not easily seen from south of the equator.
   The ZHR (average hourly rate) for this meteor shower ranges from 60 to several hundred. Best time for viewing is before sunrise as your part of the Earth is rotating toward the east sort of putting you headfirst into the meteor shower. To find the radiant for this meteor shower look for the stars of the Big Dipper and then look below the end stars in the handle.

Boötes the Herdsman

Boötes the Herdsman

   The radiant is the area from where the meteors seem to radiate outward from. Meteor showers owe their name to the constellation region the radiant is located within, and as this graphic shows the radiant is within the boundary of the constellation Boötes the Herdsman. So why the name Quadrantids?
   On some of the older star charts there is a now ‘extinct’ constellation called Quadrans Muralis, the Mural. This was a constellation located between Boötes and Draco the Dragon that was created in 1795 by French Astronomer Jérôme Lalande. It is a picture, or mural, of a Quadrant that had been used to map the stars. The Quadrantids Meteor Shower was named for the no longer used constellation.


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Circumpolar Motion

   Last night, June 3rd, I sat outside for a while just enjoying dark cities from within the city limits of Tucson. My primary view from my brother’s backyard is toward the north and the mountains in that direction so it is sort of logical, I guess, to take pictures of the night sky like this one showing circumpolar motion.
   The animated graphic is made from a series of 24 exposures all taken over a 15 minute time span and all using the same camera settings: 6 sec.; f4.5; ISO 1600; 20mm focal length. The result is this picture that is a combination of the 24 exposures stacked together using the Freeware program StarTrails.


Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Follow the Arc to a Pulsar!

   During Spring in the northern hemisphere, the seven bright stars that form the Big Dipper are easily seen high over the northern horizon. Located at the hindquarters of the Great Bear (Ursa Major), this asterism (group of stars) has long been used as a celestial guide by travelers. During the American Civil War, slaves memorized a song called “Follow the Drinking Gourd” that helped them locate the stars that would point their way to freedom. By walking in the direction of the ‘drinking gourd’ stars the escaping, freedom seeking slaves, would be following a northerly route taking them away from the slave states to the free states to the north, or to Canada.
   There is an ‘old’ Astronomical saying, a sort of memory aid, for finding at least two constellations by way of their alpha, or brightest star in their respective constellation. In Bootes the Herdsman there is the orange-reddish star Arcturus, and in Virgo the Harvest Maiden the bluish-white star Spica. The saying – “follow the arc to Arcturus, then speed to Spica” is how you connect these two stars with the curve, or arc, in the handle of the Big Dipper.
   Simply look toward the northeast to find the 7 stars making up the Big Dipper. Then look for the curved handle and follow the arc or curved handle toward Arcturus and then continue on to Spica. This is typically done during the Northern Hemisphere spring and summer season when Bootes and Virgo are in the evening skies.
   While you are looking toward this region of the sky, you can also investigate some of our neighboring solar systems.
   Scientists now believe that two sunlike stars in this region have at least one orbiting satellite each, and that a nearby pulsar could have up to three satellites. Just below the bowl of the Big Dipper lies 47 Ursa Majoris, a star with an orbiting object estimated to have two to three times the mass of Jupiter and a revolution rate of 1103 Earth days. Near the northern boundaries of Virgo, an object orbiting around 70 Virginis is estimated to have six to seven times the mass of Jupiter and a revolution rate of 117 Earth days. Although the objects themselves are too far away to be seen, the suns around which they orbit are visible to the naked eye.
   A third solar system you could direct your attention to is also within the boundaries of Virgo. Unlike the other two solar systems, the objects in this system orbit a pulsar, PSR 1257+12. A pulsar is a small, extremely dense, and rapidly rotating neutron star, a remnant of a massive star that has collapsed into itself following a supernova event. PSR 1257+ 12 gets its name from its celestial coordinates, 12 hours 57 minutes right ascension and 12o north declination. This pulsar is one of at least several known pulsars in our galaxy and this one has an estimated diameter of 16 km, and a mass that is one to two times that of our Sun.
pulsar   Pulsars earn their name from the radio waves they emit, which we receive in regular pulses. Pulsars emit radio waves as a narrow beam, much like the beam of light emitted from a lighthouse. Just as direct light from a lighthouse sweeps past a point regularly, so does the beam of radio waves emitted from a pulsar. PSR 1257+ 12 emits radio waves that reach the Earth with at an interval of 6.2 milliseconds. Because we receive pulsed radio waves from a pulsar as a result of its rotation, we know a pulsar’s pulse interval coincides with its period of rotation. This means that PSR 1257 + 12 rotates every 6.2 milliseconds!
kepler   Exo-solar systems and their planets have been detected through various methods with the greater majority of these exo-solar systems being discovered by the Kepler orbiting observatory. To date more than 1,000 objects have been confirmed as an exo-planet, with more than 4,600 objects waiting confirmation.
distant-worlds-cover   Download a series of monthly star maps and data pages. Each monthly star map shows the location of many of the stars we know or are reasonably certain that are stars with their own planets. Click here to download the “Where Are the Distant Worlds Star Maps”. (2-3 Mb PDF)

Caution: Objects viewed with an optical aid are further than they appear.
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Asteroid 2012-DA14

   Last year Spanish Astronomers at the La Sagra observatory discovered Asteroid 2012-DA14 as part of their sky survey program of searching for Small Solar System Bodies orbiting the Sun but near Earth. asteroid animationThis asteroid is estimated to be about 45 meters in size and its orbit truly classifies this object as a ‘near Earth’ object as it will be as close as 17,000 miles when it passes the Earth on the 15th of February. This not only makes it one of the closest flybys but the asteroids path takes it through the space around the Earth where we have geosynchronous satellites. However an emphasis should be placed here in that despite misinformation already online this asteroid will not hit the Earth this time around or anytime in the predictable future.
10pm   Asteroid 2012-DA14 will follow a path past the Earth that while taking it close to us will not mean that it will become naked-eye visible. Predictions suggest that it will reach around 8th magnitude, beyond what we can see with our unaided eyes. But with binoculars and certainly telescopes it may be visible as moves quickly through the stars of the Big Dipper’s bowl – as the animated graphic above shows. The animation is set for 1-hour intervals starting at 9 pm CST. Based on this the asteroid passes between the two stars marking the handle side of the dipper’s bowl, Phecda and Megrez. At approximately 9 pm the asteroid will be less than 1 degree from Phecda as the lower graphic shows.

   This could be an interesting photography opportunity – capturing the asteroids motion through this part of the sky. The 15th may be the best night as the relative speed of the asteroid carries it quickly past the Earth and about as quickly its magnitude also fades.

Additional Information
   NASA will broadcast the asteroid flyby tomorrow afternoon over NASA TV. Click here for the press release and links to NASA TV.

   AGI, the Analytical Graphics folks have produced an animation showing the flyby from the perspective of the asteroid. Click here to see the animation.

Click here to go to the Qué tal in the Current Skies web site for more observing information.

Follow the Arc

Follow the Arc

No I’m not Noah and this is not the “Ark”!
Last night I had my first meeting with my Tu/Th evening class and so we went out around 8:30 for a look at the Moon, Mars, Saturn, and other celestial objects bright enough to be seen in the light polluted skies on campus.

So once I pointed out the trio of planets and star, plus the crescent Moon I directed their eyes toward the star Arcturus and then over to the handle of the big Dipper at which point I said those famous words: “Follow the arc to Arcturus and then speed to Spica“. This got their attention so I showed how them to find the North Star and about that time the ISS flew past our location going from north to north east giving us a couple of minutes of viewing.

As the graphic shows the waxing crescent Moon is still near the trio and the arc is still follow-able!