URSA MAJOR
(April schedule, May schedule, June schedule and July schedule)

     Ursa Major constellation is visible throughout the year, except part of it which sets bellow the northern horizon. It is in best position for evening observing in April when it is high on the northeastern sky and part of it is at the zenith and in May when it is high on the northwestern sky.
     In January and February during the evening it is climbing on the northeastern sky, in March it moves higher on the northeastern sky, in April it is high on the northeastern sky and part of it is at the zenith, in May it is high on the northwestern sky, in June is on the northwestern sky, in July and August is low on the northwestern sky, in September, October, November and December is very low over the northern horizon and part of it is bellow the horizon.
     We will observe it in April when it is high on the northeastern sky and part of it is at the zenith, in May when it is high on the northwestern sky, in June when it is on the northwestern sky, and in July when it is on the northwestern sky before it gets too low.

Double and multiple stars

     Zeta Ursa Majoris - Its name is Mizar. Its visual magnitude is 2.2.
     With naked eyes close to Mizar we can notice one dimmer star with visual magnitude 4.0. Its name is Alcor and form a visual double with Mizar. They are separated on the sky about 700 arc seconds, or about 12 arc seconds, and that is about half size of the Moon"s apparent diameter on the sky. The Moon's apparent diameter on the sky is about 30 arc minutes. That is also the apparent diameter of the Sun on the sky. Alcor is main sequence star, with mass and size a bit bigger than our Sun. Alcor has companion, red dwarf separated about 1 arc second.
     If we observe Mizar through a telescope, we can notice that Mizar in fact consists of two components with visual magnitudes 2.3 and 4.0. They are separated on the sky about 14 arc seconds. Each of these two components in fact is spectroscopic binary star. These four stars are main sequence stars a bit bigger in mass and size than our Sun, and a bit hotter.
     Mizar and Alcor are about 80 light years away from the Earth and maybe they are pretty close to each other, maybe only 1 light year, but even if we suppose they are only 1 light year apart, it is questionable whether they form a true physical binary system or just move in the same direction in the space. 

     Xi Ursa Majoris - Its name is Alula Australis. Its combined visual magnitude is 3.8. It is about 26 light years away from the Earth. Through a telescope two components are visible separated on the sky only 1.7 arc seconds. Their individual visual magnitudes are 4.3 and 4.8. Their orbital period is about 60 years. This is the first binary star for which the orbital period was calculated, in the 1820s and since then it made 3 full orbits. Until around 2035 the separation will be getting bigger. Also this is the first binary star system ever discovered, by Herschel in 1780. Both are main sequence stars with almost the same spectral class as our Sun. That means they are only a fraction different than our Sun in mass and diameter, and with almost same temperature of their outer atmospheres. Both of them are in fact spectroscopic binaries probably with red dwarfs as companions. The age of this binary system is about 6 billion years.

Deep sky objects
(will be observed only from dark location outside of the city)

     NGC 2841 - It is a galaxy. It is tilted spiral galaxy, that means galaxy with spiral arms and we see it tilted on the sky. Its visual magnitude is 10.1 and it is about 45 million light years away from the Earth. Its diameter is about 150,000 light years. 

     M 81/ M 82 - Two galaxies very close to each other apparently on the sky. M 81 is almost face-on spiral galaxy. Its visual magnitude is 7.0 and it is about 12 million light years away from the Earth. Its name is Bode Galaxy named after its discoverer. M 82 is spiral galaxy which we see almost edge-on. Its name is Cigar Galaxy. Its visual magnitude is 8.4 and is also about 12 million light years away from the Earth. Its diameter is about 40,000 light years.
     Because they are close to each other, M 81 and M 82 are interacting gravitationally. The smaller galaxy M 82 is deformed in shape because of the tidal forces of the bigger galaxy M 81. This gravitational interaction also initiated rapid star formation in both galaxies - in the arms of M 81 and in the core of M 82. There are a lot of star forming regions currently in both galaxies, and also hundreds of already formed younger and older star clusters. The star formation in these galaxies is ten times more intensive than star formation in a normal galaxy, for example like in our own Milky Way galaxy. Such galaxies where star formation is intensive are called starburst galaxies.
     M 81 is dominant member of the M 81 Group of galaxies, which also includes M 82 galaxy, NGC 3077 galaxy, NGC 2043 galaxy, NGC 2366 galaxy, NGC 2976 galaxy, NGC 4236 and about 30 other smaller galaxies and dwarf galaxies. M 81 Group of galaxies is part of our Local Supercluster of galaxies.

     M 108 - It is a galaxy. It is spiral galaxy and we see it almost edge-on, so no spiral arms can be observed. It is tilted about 75 degrees to our line of sight. It has about 300 globular star clusters compared with about 150 our own galaxy has. It lies about 50 million light years away from the Earth. This galaxy is an isolated member of the Ursa Major Cluster of galaxies, which is part of our Local Supercluster. Some of the largest members of the Ursa Major Cluster are NGC 3631, NGC 3953 and M109 Group and NGC 3726, NGC 3938 and NGC 4051. Ursa Major Cluster have only 5% mass of the Virgo Cluster, which is also part of our Local Supercluster of galaxies.

     M 97 - It is a planetary nebula. Its name is Owl Nebula. Its visual magnitude is 9.9 and it is about 2,000 light years away from the Earth. Its diameter in the space is around 2 light years. It was formed around 10,000 years ago and the star in the center of the nebula is now a white dwarf. The visual magnitude of the central star is 14.0 and its mass is about half solar mass with surface temperature about 120,000 K. 

     M 109 - It is a spiral galaxy about 80 million light years away from the Earth. Its visual magnitude on the sky is 10.6 and we see it almost face-on. This galaxy is main member of the M109 Group of galaxies and it is also called Ursa Major cloud, a large group of about 50 or more galaxies. M109 Group is part of our Local Supercluster.

     NGC 3953 - it is a spiral galaxy and it is one of the main members of the M109 Group of galaxies. Its visual magnitude on the sky is 10.8. 

     M 101 - It is a face-on spiral galaxy. Its name is Pinwheel Galaxy. Its visual magnitude is 7.9 and it is about 25 million light years away from the Earth. Its size is about 170,000 light years. This galaxy has several companions and gravitationaly interact with them. As a result of the gravitational tidal forces from the companions it has deformed spiral arms, but also this interaction initiated high rate of stellar formation in its spiral arms from the interstellar gas and dust present in the galaxy arms. Newly formed stars ionize the gas around them in this regions of star formation and make this regions to glow and be detected or seen on the images and are called by astronomers HII regions. There are over 1,000 HII regions registered in the spiral arms of this galaxy. 
     M101 is the most prominent member of the M101 Group of galaxies, It contains about 10 galaxies, mostly companions of M 101. One of the companions is NGC 5474 galaxy, very close on the sky to M 101, and is highly deformed because of gravitational forces from M 101. M101 Group of galaxies is part of our Local Supercluster (Virgo Supercluster).