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January 2012

EAAE Webpage EAAE Official Blog EAAE Monthly Newsletter Archive


This month the highlight news is the launch of "Sunrise Project". This project will happen for the third year and has produced fantastic pinhole camera images during the last two years. But don't forget about "Sundials Project" and "Space Art".

You can also know all about the News published on the EAAE News on the Lats Month's Highlights section.

In the Astronomical Observations sections for this month we suggest the Cassiopeia constellation and the observation of Eros near January 31st.

As image of the month we selected NGC 6369: The Little Ghost Nebula

We wish you all clear skies during the next month.

The EAAE Webteam

EAAE Sunrise Project is back again!


The EAAE is proud to announce the Vernal Equinox 2012 edition of EAAE Sunrise Project - A modern variation of the Eratosthenes Experiment. The project is a follow up of the 2010 and 2011 editions and the deadline for registration is February 20th, 2012. Project coordination is assured by Sakari Ekko, a long time member of the EAAE that has been very active in astronomical photography among other areas.

The idea of the Sunset Project is that the students use simple self-built cardboard pinhole cameras to make very long-exposure (several days) photographs of the sunrise or sunset around vernal equinox 15. – 25.3.2012. The Sun exposes its path on the image, which is sent to Sakari Ekko after the exposure for scanning. The processed images are shared and used to comprehend the latitude-dependent differences of the path of the Sun and to find the latitudes of the different locations. The images are added to the EAAE sunrise image collection for further pedagogical use of all interested teachers.

A pinhole camera image done during the 2010 edition of Sunrise project. Sunrise 17.3.-22.3.2010, Rovaniemi, Finland, 66.5ºN 25.7ºE. Very near the Arctic circle. Look at the scanned data sheet series S.

The students will develop their skills, among other things, in basic geometrical optics, the idea of camera, self-building, observing practice, Sun’s path in the sky and its effects on climate in different latitudes.

The EAAE Sunrise Project intends to promote the simultaneous development of astronomy, maths and photography skills among students.

Another pinhole camera image done during the 2010 edition of Sunrise project. Sunset, Cascais, Portugal 38º42’N 9º25’W. Photographer: Salvador M.Bruschy. Teacher: Leonor Cabral.

Project's website:


"Find a Sundial" is still open

In October EAAE has launched the sundials competition Find a Sundial is a simple competition for all students in Europe.

Sundials are part of the European Cultural Heritage and have been used since ancient Rome and Greece. In the Middle Age many towns built sundials that can be seen by everybody walking in the streets. Some of them are magnificent. Others are so discrete you can pass by them without noticing them except if you are looking for sundials.

The challenge is for students to find these sundials and tell us their story and how it works. You can use the sundial to talk about History and Science, among other areas.

Church of St. Domenico, Rabat (Malta). Image credits: Alexandre Costa.

Don't forget that the registration for participation in “Find a sundial and, … show it to us” competition has to be made until March 30th, 2012.

Your work has tol be mailed to both the Webmaster and project chairperson within the period specified.
Webmaster: Antonio Pérez Verde.
                   Email: [email protected]
Chairperson: Ederlinda Viñuales Gavín.
            Email: [email protected]

The competition winners will be announced the second fortnight of April of 2012 by email to the winners and on our website.

Send us your "Space Art"

SPACE ART is a project that aims to stimulate students to discover the universe and its beauty. Art is a perfect way to achieve this. Space Art tries to improve student's awareness about the Universe by producing drawings or make pictures of astronomical features or events.


Teachers and students are invited to send us the drawings and pictures that are made in or ut of the classroom. We will present them on our website.

Saturn, by Paulo Tiago of Escola Flávio Resende, Cinfães, Portugal.

Learn more about it at Space Art's homepage. Artistic works can be submitted until June 30th, 2012.

Space Art's webpage


Last Month's highlights from EAAE News


Janury 1st: Day 1 of the Gregorian calendar.
: . In 1925, in a meeting of the American Astronomical Society and of the American Association for Science Development in Washington, D.C., Edwin Hubble reports that he has discovered Cepheids in the "spiral nebulae". This was the beginning of the fall of the hypothesis that said that our Milky Way was the entire Universe, because it led to the discovery that we live in one of many galaxies.
In 2001, the NEAT (Near Earth Asteroid Tracking) mission discovers an asteroid with a diameter of 1.5 km that passes near Mars (2001AA). This object was dubbed with nickname of Millennium Asteroid.

Observations: First Quarter Moon (06h18m)

Luna 1


January 2nd: Day 2 of the Gregorian calendar.
History:. In 1959, the soviet probe Luna 1was launched .

: During the evening we will assist to first meeting between the Moon and Jupiter. With the passing of the hours, our satellite will approach at the giant planet to achieve the minimum separation about 4º on the 3th at 01h just before than the celestial couple will disappear under the horizon.
The Moon in its apogee, moment of farthest  distance from the Earth (distance moon center to earth center: 404.617 km, apparent diameter: 30'00).

Mars Polar Lander
January 3rd: Day 3 of the Gregorian calendar.
History:. In 1999, the probes Mars Polar Lander and Deep Space 2 were launched.
In 2000, the probe Galileo made a flyby near Jupiter's moon Europa at a height of 351 km.

Observations: Maximum of the Quadrantids  meteor shower  ZHR(Zenital Hourly Rate)=120 maximum until the 12th.
Minimum of Variable Star Algol Beta Persei at 0.2h, Magnitude=3.4mag  Max=2,1mag Period= 2,9days Eclipse begins at about 19h27m and ends at 5h05m.
Minimum of Variable Star Delta Cephei  at 1h04m , Magnitude=4,4mag
Max=3,5mag Period= 5,4days.

January 4th: Day 4 of the Gregorian calendar.
History:. In 1610, 400 years ago the next days were probably the most important days of Astronomy History.In 1609 Galileo Galilei was pointing his telescope to the sky and observed the craters of the Moon, sunspots that allow him to deduce the Sun's rotation, the phases of Venus and find the stars of the Milky Way.

After catching Jupiter, this night the Moon is going for the Pleyades, in the evening the distance between our satellite and the open cluster is about 8º. And just before the sunrise on the 5th the distance it will be less than 5º.

Venera 5
January 5th: Day 5 of the Gregorian calendar.
History:. In 1969, the soviet probe Venera 5 is launched to Venus.

Observations: This night the Moon after reaching its minimum distance to thePleyades during daylight, is going away of the open cluster. In the evening the apparent distance between the two objects will be about 5º and will increase slowly hour after hour.
The Earth in its perihelium minimum distance Earth-Sun 147,1 million  Km. The Afelium maximum distance it will be on 5th, July 152,1 million km

January 6th: Day 6 of the Gregorian calendar.
Observations: This night Earth's satellite is going for Aldebaran Alfa Tauri passing about 6º  of the star after the midnight.

Galileo Galilei

January 7th: Day 7 of the Gregorian calendar.
History:. In 1610 Galileo observed with his telescope what he described at the time as "three fixed stars, totally invisible by their smallness," all close to Jupiter, and lying on a straight line through it. Observations on subsequent nights showed that the positions of these "stars" relative to Jupiter were changing in a way that would have been inexplicable if they had really been fixed stars. On January 10th, Galileo noted that one of them had disappeared, an observation which he attributed to its being hidden behind Jupiter. Within a few days he concluded that they were orbiting Jupiter: He had discovered three of Jupiter's four largest satellites (moons): Io, Europa, and Callisto.

Observations: Take your telescope and observe Jupiter:
First, at 18h32 Galilean Moon Io will disapear behind the planet. You will not see the satellite until 21h59 when it reappears after being eclipsed by the shadow of the giant planet.
After, from 19h45 until 22h10 the shadow of the Galilean satellite Europa will transit over the planet. Try to see this really dark spot.
Finally try to see the Great Red Spot from 21h until 22h (GRS will transit at 21h38).


Valeri Polyakov

January 8th: Day 8 of the Gregorian calendar.
History:. In 1977 the soviet mission Luna 21 was launched.
In 1994, the Russian cosmonaut Valeri Polyakov departs on the Soyuz TM-18 to Mir. where he will stay until March 22nd, 1995, with a record of 437 days in Space.

Observations: Continuing with Jupiter (through the telescope),  if you live in the Eastern Europe, try to see the Great Red Spot until 17h from 18h (GRS will transit at 17h29). From western Europe, during the event, the sky will be not completely dark, due to twilight.
If you had no luck with the Great Red Spot, an easier target will be try to distinguish the shadow of Io over the planet from 17h04 until 19h15 as a dark spot that moving slowly.

January 9th: Day 9 of the Gregorian calendar.
Observations: Full Moon (07h30).
This evening the Moon passes between Procyon Alfa Canis Minoris and Pollux Beta Gemini at about 11º of each star.

Venera 6

January 10th: Day 10 of the Gregorian calendar.
History:.In 1969, the probe Venera 6 (USSR) was launched. It reached Venus on May 17th, 1969. The atmospheric research send back data to Earth until 11 km above surface where the probe was destroyed.


Observations: Until the 24th (when the Moon will return to early evening), look for the zoodiacal light. This is a good time for observation low above the West-Southwest horizon 80 to 120 minutes after the sunset from dark locations at mid-northern latitudes.
If you could use a telescope, try to see The Great red Spot over Jupiter, from 18h to 20h (GRS transit at 19h08).


January 11th: Day 11 of the Gregorian calendar.
History:. In 1787, William Herschel discovers Oberon and Titania, the biggest moons of Uranus.

Observations: Tonight the Moon in its race across the ecliptic, is going for Regulus Alfa Leonis, approaching to the star, hour after hour.  Just before midnight it will be at 8º to the star.
Ceres about 9º at South of Uranus.

January 12th: Day 12 of the Gregorian calendar.
History:. In 1820 the "British Royal Astronomical Society" is founded.
In 2005 the probe Deep Impact was launched from Cape Canaveral.

After passing at its minimum distance of about 6º of Regulus,  the Moon tonight, is going away slowly of this star.  Look at the Eastern horizon some minutes before 21h and you could see the rising Moon and some minutes later, Regulus at about 8º from our satellite.
Maximum libration of 7,9º on the North-Ouest edge of the Moon marked by chaining of the craters South, Babbage and Pythagoras.


January 13th: Day 13 of the Gregorian calendar.
History:. In 1610, Galileo discovered the fourth Galilean moon, Ganymede.
In 2000, black holes were discovered drifting along the Galaxy.

Observations:Neptune will be at only 1,1º to North of Venus on the evening sky. To observe this planetary embrace you must need a dark sky with Neptune at 8th magnitude.  In western Europe the observations could begin about 18h with the planetary couple at about 12º over the South Western horizon. It will be mandatory a clear sky to distinguish Neptune with binoculars or through another instrument which offers a field of at least 1,5º for example a telescope with focal length of less than 1m with a wide field eyepiece. Use Venus (magnitude -3,8) as a reference point to locate Neptune. 
The Moon will rise together Mars in the middle of the night. About 22h, examine the East horizon to see appear the Moon and Mars. One hour later the red planet will be at 8º of the Moon and at the same distance to Denebola B Leo the second brighter star of Leo. Rising  in the sky, the Moon, will going away slightly of Mars.
The asteroid Laetitia in opposition with magnitude 10 close to Beta Canis Minoris.

Huygens probe landing.

January 14th: Day 14 of the Gregorian calendar.
History:. In 2005 the probe Huygens landed on Saturn's moon Titan.

Observations: If you can use a telescope, tonight is a good nitght to see the Great Red Spot over Jupiter, from 22h to 23h (GRS transit at 22h26).

January 15th: Day 15 of the Gregorian calendar.
History:. In 1965, the Soviet Union launched Soyuz 5.

Observations: Spica Alfa Virginis about 2º at North of the Moon

Crew of STS107 during mission.

January 16th: Day 16 of the Gregorian calendar.
History:. In 2007 Space Shuttle Columbia was launched for mission STS-107, that would be its last.

Observations: Last Quarter of the Moon (09h12m).
Saturn and the Moon will rise over the East South-East horizon about 02h. The last quarter Moon will be at about 9º of the ringed planet and at about 3º of Spica A Virginis during the rest of the night the Moon will approach to Saturn to achieve an apparent distance of about 8º at the moment of culmination passing the meridian, one hour before the sunrise.

The Delta2 transporter explosion

January 17th: Day 17 of the Gregorian calendar.
History:. In 2003, a Delta 2 rocket that transported GPS2R satellite explodes 13 seconds after ignition leaving 250 tons of burned debris on the launching platform.

Observations: The Moon is at its perigee, the closest distance from the Earth. Distance between moon center to earth center: 369.850 km, apparent diameter: 32'52")

January 18th: Day 18 of the Gregorian calendar.
History:. In 1896 Roentgen presented the first X-ray detector.

Observations: Mercury is at aphelion, maximum distance from the Sun.

Jacobus Kapteyn.

January 19th: Day 19 of the Gregorian calendar.
History:. In 1747, Johann Bode, the author of Titius-Bode law, was born.
In 1851, Jacobus Kapteyn was born. He created the first modern model of the dynamic of the Milky Way.

Observations: Saturn in quadrature, during this period, is when the  planet’s globe shadow over the rings is more visible.
Antares Alfa Scorpii about 5º at South of the Moon

The Crab Nebula.

January 20th: Day 20 of the Gregorian calendar.
History:. In 1969, Jocelyn Bell discovers the first known pulsar in the Crab Nebula.

Observations: This evening look at Jupiter through your telescope if you live in the Eastern Europe, try to see the Great Red Spot until 17h from 18h (GRS will transit at 17h27). From western Europe, during the event, the sky will be not completely dark, due to twilight.

January 21st: Day 21 of the Gregorian calendar.
History:. In 2004, NASA "lost" contact with the rover Spirit, a problem that would be solved remotely on February 6th.

Observations:Try to see the Comet P/2006 T1 Levy, tonight is at its minmum distance to us, reaching magnitude 7 on the constellation of Cetus. It coud be visible through binoculars.

Roberta Bondar.

January 22nd: Day 22 of the Gregorian calendar.
History:. In 1968, Apollo 5 was launched transporting the first lunar module.
In 1992, Roberta Bondar became the first Canadian woman in Space on board of the STS-42.
In 2000 the launch platform Vandenburg was demolished.
In 2003, contact with the probe Pioneer 10 was lost.

Observations: Jupiter in quadrature.


January 23rd: Day 23 of the Gregorian calendar.
History:. In 1987, a supernova in the Great Magellanic Cloud became visible as the result of the explosion of the blue supergiant Sanduleak 69. Known as SN1987A, it was the first "close" supernova of the last three centuries.

Observations: New Moon (07h42).

Polar probe's mission impression.

January 24th: Day 24 of the Gregorian calendar.
History:. In 1969 the probe Mariner 6 was launched.
In 1979, the probe Solwind P78-1was launched.
In 1996 the probe Polar was launched.

Observations:Try to catch the young Moon only 34h old on the evening sky about 40 minutes after the sunset. Find the thin crescent about 10º over the Wet South-West horizon.
The Asteroid Pallas about 8º at North of the Moon.

Mars Rover.

January 25th: Day 25 of the Gregorian calendar.
History:. In 2004, the rover Opportunity(MER-B) lands on the surface of Mars.

Observations: Mars Stationary getting retrograde.
Neptune about 6 º at South of the Moon.

January 26th: Day 26 of the Gregorian calendar.
History:. In 1978 the satellite "International Ultraviolet Explorer" (IUE) is launched into a geosynchronous orbit.

Observations: Venus will be at less than 6º to the South of crescent Moon, one hour after the sunset. This beautiful meeting will occur at more than 20º high over the horizon so it will be really easy to observe.
 Maximum libration 7,2º on Mare Australis zone close to the crater Lyot.

Apollo 1 crew.

January 27th: Day 27 of the Gregorian calendar.
History:. In 1613, Galileo observes for the second time Neptune, marking it as a star (the first time was in December 28th, 1612).
In 1967, the astronauts of Apollo 1 - Virgil (Gus) Grissom, Edward H. White II e Roger B. Chaffee - are killed in a fire during test Apollo 204 (AS-204), of what was intended to be the first manned mission to the Moon.

Observations: Tonight we will return to Jupiter: If you could use a telescope, try to see The Great Red Spot over Jupiter, from 17h to 19h (GRS transit at 18h15).

Johannes Hevelius.
January 28th: Day 28 of the Gregorian calendar.
History:. In 1611, Hevelius was born. He would be the first astronomer to observe the phases of Mercury and he died on the same day in 1687.
In 1986, Space Shuttle Challenger explodes 73 seconds after take-off.

Observations: Uranus about 6º at South of the Moon.

January 29th: Day 29 of the Gregorian calendar.
History:. In 1986 the incident Height 611 occurred.

Observations:Another great chance  to see the Great Red Spot over Jupiter, from 19h to 21h (GRS transit at 19h54).


January 30th: Day 30 of the Gregorian calendar.
History:. In 1964, the probe Ranger 6 was launched.
In 1996, Comet Hyakutake was discovered by Yuji Hyakutake.

Observations: For the second time in January, the Moon, catches Jupiter again, after a complete turn around the sky. This time the minimum distance will be 4,3º but it will occur when the pair it will be really high in the sky in the latest hours of the twilight.
The asteroid Vesta about 5º at South of the Moon.

Explorer 1.

January 31st: Day 31 of the Gregorian calendar.
History:. In 1862, Alvan Graham Clark Jr. discovers the faint companion of Sirius, dubbed Sirius B.
In 1958, Explorer I, the first American satellite was launched.
In 1966, Luna 9 was launched.
In 1971, Apollo 14 was launched to the Moon.

Observations: The asteroid 433 Eros at its minimum distance to Earth 26,7 million km (see Advanced Astronomical Observations in this Newsletter).
First Quarter Moon (04h12)


The Queen Cassiopeia
by Jordi Delpeix

For this month, we have selected the Cassiopeia constellation, a nice and curious shape, northern constellation. Its myth in the Greek mythology is one of the nicest:

Mythological representation of the constellation Cassiopeia.

In old star charts Cassiopeia is usually depicted in the sky on her throne, still combing her hair.
In the Greek mythology, Cassiopeia, the wife of King Cepheus (represented by the neighbouring constellation Cepheus in the sky), was the beautiful queen of the mythological Phoenician kingdom of Ethiopia. She was so proud of her beauty that she became arrogant and vain: Cassiopeia offended the Nereids by boasting about being more beautiful than all them. The Nereids were sea nymphs all daughters of Nereus, and one of them, Amphitrite, was married to Poseidon (Neptune), the Greek sea god. This boast angered Amphitrite and her sisters and asked the ruling god of the sea, Poseidon, to punish Cassiopeia. Poseidon, enraged, thought that these kind of acts and comments coming from a mortal could not go unpunished and this way Cassiopeia’s comments brought the wrath of Poseidon, upon the kingdom of Ethiopia.

The sea god was angry and therefore sent the giant sea monster, Cetus, represented by the constellation Cetus (the Whale), located in the same region of the sky, to destroy their kingdom of Ethiopia.

Trying to save their kingdom, Cepheus and Cassiopeia consulted the old wise oracle of Ethiopia for advice, who told them that the only way to appease the sea gods was to sacrifice their beautiful daughter Andromeda to the sea monster.

Although they were heartbroken reluctantly, they did so, leaving Andromeda chained to a rock at the sea’s edge for the monster to find as a sacrifice and left there to helplessly await her fate at the hands of Cetus.

But the hero Perseus heard her cry and immediately flew to her rescue, he arrived in time to rescue her from the monster’s jaws riding on Pegasus the great magical winged horse! Perseus discovered and held up the ugly head of Medusa as Cetus approached. The sea monster was immediately stopped, since anyone who looked directly at the head of Medusa was turned into stone. Perseus carefully placed the head back in its sack, taking care that Andromeda would not look at it. He then unchained Andromeda who fell into his arms. When they gazed into each other’s eyes they immediately fell in love.

Poseidon was so touched by the love of Perseus and Andromeda that he placed them next to each other in the heavens so that their love will always be seen and felt by us on Earth.

Since Poseidon thought that Cassiopeia should not escape punishment,  placed Cassiopeia and Cepheus next to each other in the sky among the stars in a position where she is  condemned to circle around the North Celestial Pole forever, As an added punishment for her vanity, half of the time hanging in an upside-down position in undignified posture.

The constellations of Perseus, Pegasus, Andromeda, Cetus, Cepheus and Cassiopeia, are represented as a neighbouring constellations located in the same region of the sky.

How to find it:

The constellation is quite easy to spot in the sky because five of its bright stars form a distinctive 'W' shape. Identifying the Cassiopeia constellation makes it easy to identify many surrounding constellations. It is surrounded by the Andromeda constellation on the south, Cepheus constellation in the North, Perseus constellation on the south east. If we know its approximate position, there is no way that we can miss it.

The Cassiopeia constellation this month early in the evenings, showing an M shape.
(Click on the image to see a bigger version.)

On January, about two hours after the sunset when the sky is completely dark, look at the zenith (the point of the sky directly over your head), the Cassiopeia constellation is very high in the sky close to the zenith. When the constellation is in culmination high in the sky, its stars have an M shape (an inverted W shape).

The Cassiopeia constellation this month at dawn, showing  its caracteristic W shape.
(Click on the image to see a bigger version.)

This month, about 2h before the sunrise the arrangement of the five brightest stars resembles a slightly extended letter W when it is low above the northern horizon.

Cassiopeia is always in opposite position to Ursa Major « The Big Dipper » from the Polar star α Ursa Minoris (the celestial north pole): when Ursa Major is above the Polar star (and of course Ursa Minor), Cassiopeia lies below it, low close to horizon and vice versa. When Ursa Major is on the left side of Polar going down, Cassipeiae is on the right side going high and vice versa.

The constellation:
Cassiopeia is famous for its distinctive W shape, an asterism formed by five bright stars in the constellation, ranging from magnitude 2 to 3,5 marking each turn in the W.

It can be seen at latitudes between +90° and -20° but Like Ursa Major, the splendid constellation Cassiopeia is circumpolar in the mid-northern latitudes. This means that we can see it every night and for the whole night. It never rises or sets.

Cassiopeia lies in the Milky Way, so the entire area is rich in stars and many objects like nebulae (clouds of gas and dust) and star clusters lie within it. Scanning Cassiopeia with binoculars will reveal many of them though not the nebulae.

The Cassoipeia constellation's map.
(Click on the image to see a bigger version.)

The stars from right to left are Beta (β), Alpha (α), Gamma (γ), Delta (δ) and Epsilon (ε) Cassipoiae.

Beta (β) Caph ("palm") is a yellow-white giant with a magnitude 2,3 (remember that the lowest the number of magnitude scale, the brightest the star is). It is 2-4 times the size of the Sun and 25-30 times brighter. It is the 74th brightest star in the sky. Since it is a mere 50 light years away from us, it is considered to be our close neighbor. It is currently in the process of cooling down and will eventually become a red giant.
Together with the stars Alpheratz α Andromedae and Algenib γ Pegasi, Caph was known as one of the Three Guides; three bright stars marking the equinoctial colure, the imaginary line from Caph to Alpheratz to the celestial equator, at a point where the Sun crosses it at each spring and autumn equinox.

The yellow-orange Alpha (α) is located at the bottom right of the W asterism and has a magnitude of 2,2 and is the second brightest star in the constellation. The star’s traditional name, Schedar, is derived from the Arabic şadr, which means “breast.” The name refers to the star’s position, marking Cassiopeia’s heart. It is an orange giant more than 500 times brighter than the Sun. It is the 71st brightest star in the sky, and according to the Hipparcos astrometrical satellite,  the star is about 230 light years away from us.  Its spectral type is K0 IIIa, a type of star cooler but much brighter than our Sun.

The next star in line towards the pole is Gamma (γ), the central star in the W shape and currently the brightest star in the constellation. It is a blue star, about 600-700 light years away. Its luminosity is thousands of times that of the Sun and having about 15 solar masses. Gamma is an eruptive irregular variable star. It exhibits irregular variations in brightness, which ranges between 1,6 magnitude and 3,4 magnitude. The apparent magnitude of this star was +2.2 in 1937, +3.4 in 1940, +2.9 in 1949, +2.7 in 1965 and now it is +2.15. At maximum intensity (currently 2.15), the star outshines both alpha and beta Cassiopeiae. The star rotates very rapidly and bulges outward along the equator. As a result of its fast spinning, a ‘decretion’ disk of lost mass and material forms around the star, which causes the fluctuations in luminosity.
It does not have a traditional Latin or Arabic name,but it has the nickname Navi, which it got from the American astronaut Virgil Ivan Grissom, Navi is Ivan spelled backwards. The star was used as a navigational reference point by astronauts during space missions.

Now move over to Delta (δ), the star’s traditional name, Ruchbah, comes from the Arabic rukbah, which means “knee”. Sometimes the star is also known as Ksora. Is an eclipsing binary star. It has an apparent visual magnitude 2,7 is the 108th brightest star in the sky. Its light travels approximately 100 years to reach us. Its luminosity is 61 times that of the Sun. It is the fourth brightest star in the constellation.

Last in line on the end is Epsilon (ε) Cassiopeiae, also called Segin,  is a single, bright blue-white B spectral type giant; about 500 light-years away from Earth. Its luminosity is more than 1.000 times that of the Sun. It has an apparent visual magnitude of 3,4. The star’s estimated age is 65 million years and it is at the end of the hydrogen-fusing cycle.

Eta (η) Achird has an apparent magnitude of 3,4 and is only 19 light years away from Earth, is the nearest star in Cassiopeia to our solar system. Is a wonderful double star that can be separated even through small telescopes, The orbital period of this binary star is approximately 500 years, consisting of a yellow dwarf similar to our Sun and an orange dwarf.  The primary star in the η Cassiopeiae system is a yellow dwarf (main sequence star) of spectral type G0V, putting it in the same spectral class as our Sun, which is of spectral type G2V. It therefore resembles what our Sun might look like if we were to observe it from η Cassiopeiae. It is really similar to the Sun; a yellow-white G-class hydrogen fusing dwarf, slightly cooler than the Sun with a surface temperature of 5730 Kelvin. The star has a cooler and dimmer (magnitude 7.51) orange dwarf companion of spectral type K7V. The two stars are separated by an average distance of 71 AU, where an AU is the average distance between the Sun and the Earth. However, the large orbital eccentricity of 0.497 means that their periapsis, or closest approach, is as small as 36 AU. For comparison, the semi-major axis of Neptune is 30 AU.

Two of the most luminous stars in the entire galaxy lie in Cassiopeia constellation region and  are visible to the unaided eye. One is (ρ Cassiopiae) and the other one is V509 Cassiopeiae they are also among the most distant stars visible to the naked eye in the Milky Way galaxy.

ρ (Rho) Cassiopeiae belongs to a very rare class of stars, the yellow hypergiants, only seven of which are currently known in the Milky Way Galaxy. It is located approximately 11.650 light years away from Earth. In spite of the distance, Rho Cassiopeiae is one of the most luminous stars known and is visible to the naked eye.

Rho Cassiopeiae is 550.000 times brighter than the Sun!! With an absolute magnitude of -7,5.  Its apparent visual magnitude varies from 4.1 to 6.2.  Its surface diameter measures 450 times that of the Sun, or approximately 630.000.000 kilometers. The star is classified as a semiregular variable. It undergoes enormous outbursts roughly every 50 years, resulting in change in luminosity. In 2000-2001, the star ejected about 10.000 Earth masses in one of these outbursts.

V509 Cassiopeiae is another G-type hypergiant, at least 7.800 light years distant. The yellow-white star is classified as a semiregular variable. Its luminosity varies between magnitudes 4,75 and 5,5.

In early November of 1572, a new star appeared in the constellation of Cassiopeia, it was a Supernova, one of about eight supernovae visible to the naked eye in historical records. It rivaled Venus in brightness! The supernova remained visible to the naked eye into 1574, gradually fading until it disappeared from view. Tycho Brahe did extensive work in both observing the new star and in analyzing his own observations and those of many other observers. But Tycho was not even close to being the first to observe the 1572 supernova, although he was apparently the most accurate observer of the object. This way is known as the Tycho's supernovae.

The constellation Cassiopeia contains three stars with known planets.

A curious fact about Cassiopeia is that if you could reach Alpha Centauri (the closest star to our solar system), then look towards our Solar System, observed from there our Sun it would appear in Cassiopeia as a yellow-white 0,5 magnitude star. The famous W of Cassiopeia would become a zig-zag pattern with the Sun at the leftmost end, closest to ε Cas.

The Cassoipeia constellation seen from Alpha Centauri.
(Click on the image to see a bigger version.)



Asteroid 433 Eros Visits The Earth
by Jordi Delpeix

On January 31, 2012, The asteroid 433 Eros will pass the Earth at 0,17 AU (26,7 million km, about 70 times the distance to the Moon, with a visual magnitude of 8,6. During the whole month it will be visible through binoculars. The event deserves to be followed even if the brightness of Eros is not spectacular, far from it.

In January, Eros is visible under good conditions from 23h30 to 05h (U.T.).

(433) Eros from  NEAR Shoemaker probe.
(Click on the image to see a bigger version.)

An asteroid is a small, rocky object that orbits the Sun. Most asteroid orbits are between the orbits of Mars and Jupiter and, like Mars, most asteroids are much closer to us at opposition than at other times. There are, however, asteroids all over the Solar System, and some of them occasionally pass close to Earth. One of them may eventually hit us...

A large majority of known asteroids orbit in the asteroid belt between the orbits of Mars and Jupiter  in relatively low-eccentricity (not very elongated) orbits. This belt is now estimated to contain more than one million asteroids larger than 1km  in diameter, and millions of smaller ones. These asteroids may be remnants of the protoplanetary disk, and in this region the accretion of planetesimals into planets during the formative period of the Solar System was prevented by large gravitational perturbations by Jupiter.

The first asteroid to be discovered, Ceres, was found in 1801 by Giuseppe Piazzi, and was originally considered to be a new planet. This was followed by the discovery of other similar bodies. The astronomer Sir William Herschel proposed the term "asteroid", from Greek  'star-like, star-shaped'.

Asteroids vary greatly in size, from almost 1000 kilometres for the largest down to rocks just tens of metres across. The three largest are very much like miniature planets: they are roughly spherical, have at least partly differentiated interiors, and are thought to be surviving protoplanets. The vast majority, however, are much smaller and are irregularly shaped; they are thought to be either surviving planetesimals or fragments of larger bodies.

Ceres is by far the largest asteroid, with a diameter of about 975 km and contains about 25% of the mass of all the asteroids combined. The next largest are 2 Pallas, 4 Vesta and 10 Hygiea which are between 525 and 400 km in diameter. All other known asteroids are less than 340 km across. There are 26 known asteroids larger than 200 km in diameter. The total mass of all the asteroids is less than that of the Moon.

Ceres is the only asteroid large enough for its gravity to force it into a spheroidal shape, and so, according to the IAU's 2006 resolution on the definition of a planet, it has been classified as a dwarf planet, the only one in the inner Solar System. Although there are several large asteroids (Vesta, Pallas, and Hygiea) that may be classified as dwarf planets when their shapes are better known. The rest of the asteroids have irregular shapes.

Asteroid shapes.
(Click on the image to see a bigger version.)



Asteroids are classified into three main groups according to their chemical composition: C-type, S-type, and M-type. C-types for dark  carbon-rich (carbonaceous objects) about 75% of known asteroids, S-types for stony (silicaceous) objects about 17% of known asteroids and M-type, for metallic, most of the rest: pure nickel-iron.  There are also a dozen or so other rare types.

Asteroids are also categorized by their position in the solar system:

  • Main Belt: located between Mars and Jupiter roughly 2 – 4 AU from the Sun.
  • Trojans: co-orbital with Jupiter located near Jupiter's Lagrange points (60 degrees ahead and behind Jupiter in its orbit).  Curiously, there are many more in the leading Lagrange point (L4) than in the trailing one (L5).
  • Near-Earth Asteroids (NEAs): ones that have orbits that pass close to that of Earth.

Asteroids according to their position in the Solar System.
(Click on the image to see a bigger version.)

There are three families of near-Earth asteroids:

  • Atens: which have average orbital radii less than 1.0 AU and aphelion distances greater than 0.983 AU (Earth's perihelion), placing them usually inside the orbit of Earth.
  • Apollos: which have average orbital radii greater than 1.0 AU and perihelion distances less than 1.017 AU Earth's aphelion
  • Amors: which have average orbital radii in between the orbits of Earth and Mars and perihelion slightly outside Earth's orbit (1.017–1.3 AU). Amors often cross the orbit of Mars, but they do not cross the orbit of Earth.


Many Atens and all Apollos have orbits that cross (though not necessarily intersect) that of the Earth, so they are a threat to impact the Earth on their current orbits. Amors do not cross the Earth's orbit.

NEAs survive in their orbits for just a few million years. They are eventually eliminated by planetary perturbations which cause ejection from the Solar System or a collision with the Sun or a planet. With orbital lifetimes short compared to the age of the Solar System, new asteroids must be constantly moved into near-Earth orbits to explain the observed asteroids. The accepted origin of these asteroids is that asteroid-belt asteroids are moved into the inner Solar System through orbital resonances with Jupiter. The interaction with Jupiter through the resonance perturbs the asteroid's orbit and it comes into the inner Solar System.

The three families of near-Earth asteroids.

(433) EROS

Eros was the Greek god of love and desire. 433 Eros is a near-Earth asteroid (NEA) discovered in 1898, it is an S-type asteroid orbiting the Sun mostly between the orbits of Earth and Mars. Eros is not a sphere but an elongated peanut-shaped (or potato- or shoe-shaped) object, it is approximately 34×11×11km in size, the second-largest NEA after 1036 Ganymed, and belongs to the Amor group. Eros is a Mars-crosser asteroid, the first known to come within the orbit of Mars. Its  orbit has an average distance from the Sun about 172,8 million km. Its orbital period is 1,76 years (643,2 days) and its rotation period is 5h16m.

Eros is the first asteroid to be orbited by a probe (in 2000): The NEAR Shoemaker probe visited 433 Eros twice, first with a 1998 flyby, and then entered orbit around it in 2000 when it extensively photographed its surface and returned a wealth of images and data. On February 12, 2001, at the end of its mission, it landed on the asteroid's surface



The term asteroid means “starlike” and describes exactly how asteroids appear in a telescope; they are tiny points that never show any surface detail.

The main way to distinguish an asteroid from a star is by its motion. For observers with CCD cameras, however, two kinds of scientifically useful observation are possible, astrometry (precise position measurement) and photometry (measurement of brightness, especially short-term variations). Brightness is of interest because many asteroids change brightness appreciably as they rotate, making it possible to infer the shape and rotation period of the asteroid.

(433) Eros and Earth's orbits and position on January 31st.
(Click on the image to see a bigger version.)


During rare oppositions, every 81 years, such as in 1975 and 2056, Eros can reach a magnitude of 7,which is brighter than Neptune and brighter than any main-belt asteroid. Vesta is the only main-belt asteroid that can, on occasion, be visible to the naked eye. On some rare occasions, a near-Earth asteroid may briefly become visible without technical aid; Under this condition, the asteroid actually appears to stop, but unlike the normal condition for a body in heliocentric conjunction with the Earth, it never appears to be retrograde. Its synodic period of over 846 earth days is among the largest of any body in the Solar System. Eros will reach its opposition on 1st of March 2.012.

On January 1st Eros will be at 0,23 UA and it will shines like 9,4 magnitude star, reachable through binoculars. On January 15th it  will be at 0,23 UA and it reaches magnitude 8,9. See the ephemerides below.

From January 28th to February 4th, Eros will be at 0,179 UA from Earth, with the minimum distance (perigee) on January 31th when it will be at 26,73 million km from our planet with an apparent magnitude about 8,6.

These approaches at less than 0,2 UA are rares and they happened only twice after its discovery in 1.898: in 1.975 (0,151 UA) and in 1.937 (0,174 UA).

After 2.012 we will wait until 2.056 (0,15 UA) with an approach at 0,209 UA in 2.019.




Time zone=CET





(433) Eros

Date Coord.








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Rotation of 433 Eros


ESA App for iPod and iPAD is our choice of the month.

ESA's Application for iPhone and iPad. Image credit: ESA.

Space in your pocket…and also on your tablet! The new ESA iPhone or iPad application, or ‘App’, can now deliver a wealth of information on ESA missions, videos, images and news updates, at your fingertips.

All ESA features are now available in a single App that you can use to browse through ESA's content and media.

Learn more about it at

NGC 6369: The Little Ghost Nebula. Image credit and copyright:Hubble Heritage Team, NASA
(click on the image to see a bigger version)

This is a fantastic false-color composition of the planetary nebula NGC 6369, that was discovered by 18th century astronomer William Herschel as he used a telescope to explore the medicinal constellation Ophiucus. Round and planet-shaped, the nebula is also relatively faint and has acquired the popular moniker of Little Ghost Nebula. Over 2,000 light-years away, the Little Ghost Nebula offers a glimpse of the fate of our Sun, which could produce its own planetary nebula only about 5 billion years from now. Planetary nebulae in general are not at all related to planets, but instead are created at the end of a sun-like star's life as its outer layers expand into space while the star's core shrinks to become a white dwarf. The transformed white dwarf star, seen near the center, radiates strongly at ultraviolet wavelengths and powers the expanding nebula's glow. The nebula's main ring structure is about a light-year across and the glow from ionized oxygen, hydrogen, and nitrogen atoms are colored blue, green, and red respectively.

European Association for Astronomy Education