October 2018 Sky Calendar

Mercury – Mercury is in the western evening skies this month, but this apparition is not very good for viewing Mercury. To start the month it is too close to the Sun to seen, by the end of the month it rises up a little and it might be possible to see. By months end it is up for 50 minutes, being only 7° high at sunset. This month its phase will go from 98% up to 75%, it size from 4.8 arc-seconds to 5.9 arc-seconds and it magnitude from -0.9 to -0.2.

Venus – As Venus approaches inferior conjunction with the Sun on the 26th of this month, it is very low right after sunset on the western horizon to start the month. After the first week of the month it probably will be too close to the Sun to see. To start the month it is up only about 45 minutes with it being only 6° high at sunset. It will be a very large crescent with a phase starting at 17% to begin the month and then getting even thinner during the month. It size will go from 46.4 to 61.1 arc-seconds, with a magnitude going from -4.8 to -4.2 for the month.

Jupiter – As Jupiter approaches conjunction with the Sun next month it is getting lower in the evening south-western skies and not up for very after sunset. To begin the month it is up for about 2 hours this month after sunset, being only about 17° high when the Sun sets. This shrinks down to Jupiter being only up for 1 hour and only being 9° high after sunset by the end of the month. During the month the size goes from 32.6 to 31.3 arc-seconds with a magnitude around -1.8.

Mars – As we are moving away from Mars it is getting smaller and will be more difficult to see details on it. It is best to try to view in when it highest up in the southern skies which is an hour or two after sunset. It is still up for about 7 hours after sunset for the month. It is size during the month goes from 15.8 and 12 arc-seconds with it dimming as the month goes on with its magnitude decreasing during the month going from -1.3 to -0.6.

Neptune – This is still a good time to see Neptune with being only a month past opposition. It is still for a good part of the night with up for over 9 hours the whole month. It is best wait until twilight is complete over to view to give it some time to rise up some at which point it will be visible in the SE skies right after twilight. To see it when it is at its highest in the sky in the south, at start the month this will be around 22AM, by month end will it be around 10AM. During the month its size will be around 2.3 arc-seconds with a magnitude of around 7.8. This still should be a good month to try to see it largest moon Triton.

Uranus – Uranus is at opposition later this month on the 24th. Since it is at opposition it is up most of the night it being up for 11 ½ hours during the night at the start of the month and with this increasing to 13 hours at month end. It is best viewed highest up in the southern skies. To start the month it is due south around 2:30, by months end it is due south around 12:30 AM. During the month, its magnitude will about 5.7 with a diameter of 3.7 arc-seconds. At opposition will be a good time to see it larger moons. Its moon Titania will be at magnitude 13.9 and Oberon at 14.1, these are a little farther out from the planet (around 22 to 44 arc-seconds) so should be not in the planets glare. A couple fainter moons, Ariel (magnitude 14.2) and Umbriel (magnitude 15.0) are closer to Uranus (14” to 22”) so are more difficult to see.

A finder chart for Neptune and Uranus can be found at www.skyandtelescope.com/wp-content/uploads/WEB_UrNep18.pdf