SkyDiary
Image Credit: NASA/Bill Ingalls

Find out what’s up in the night sky:
Upcoming astoronomical events, interesting observations, packed with everything a stargazer needs to know.

Observations are described for the NORTHERN hemisphere and can be made by naked eye, small binoculars or by small telescope.

February 2018

Phases of the Moon

Last Quarter:February 7
New Moon:February 15
First Quarter:February 23
Full Moon:none

Jupiter, Mars and Saturn

Around the local midnight, the planet Jupiter shines brightly over the southern horizon. You can use a small telescope mounted on a solid tripod to observe its four largest moons: Io, Europa, Ganymede and Callisto. Some degrees to the left (east) and below of Jupiter there is another planet Mars. It is dimmer than Jupiter but even binoculars show its red or orange color. The planet Saturn is visible below and to the left of Mars, but it is only about 10 degrees over horizon around midnight for my latitude of 48.5 degrees north. Its observation is more convenient about 2 hours before sunrise. However, its visibility improves towards the end of February.

Mars Observation: Larger telescope is needed

As I mentioned already last year, there is a Great Perihelic Opposition of the planet Mars in year 2018, July 27, in the constellation Capricornus. If you want to see some details on its surface, you will need the telescope which can deliver rather large magnification. For the refractor, the minimal objective diameter should be around 100mm (millimeters), and for the Newton reflector the minimal mirror diameter should be around 150mm. The magnification is needed in the range 100x - 300x, so that the telescope must have the objective of a long focal length. The eyepieces must be of high quality, preferably with anti-reflex coatings of all optical boundaries. Such a telescope requires a very sturdy mounting, best equipped with the electric drive that compensates for the rotation of the sky.

Details on the Mars surface can be observed when its angular diameter on the sky exceeds 6 arc - seconds (6''). This will happen on February 12 this year. During February, there is a summer on the northern hemisphere on Mars and a winter on its southern hemisphere. The North Polar Cap (NPC) should be very small, hardly visible. Since the northern hemisphere is tilted towards the Sun (and hence also towards the Earth), the southern polar region is not observable. Moreover, the Southern Polar Cap (SPC) is hidden below fog and clouds, which consist of the water vapor and the carbon dioxide.

Article by (C) G. Okša