In the Sky This Week – August 22, 2017
avatar

Sirius, the “Dog Star,” accompanies Venus low in the eastern predawn sky. Jupiter sets shortly after dusk and will vanish from view entirely in a early September. Saturn is high in the southern sky, and with the planet’s northern hemisphere tilted towards us at about 26°, Saturn is just a spectacular observing target. The Moon, fresh from the eclipse, will be in conjunction with Jupiter in the west at dusk on August 24th and 25th. The Moon will be a waxing crescent in the west at dusk, growing larger each evening until it is at first quarter on August 28th; the later part of this week will be excellent nights for star parties. Sirius, the brightest star in Earth’s sky, is a binary star system about 8.6 light years away. Sirius A is a bright and hot main sequence star, with a faint white dwarf companion: Sirius B. Sirius A is class A0 star about twice the mass of the … Continue reading

In the Sky This Week – August 15, 2017
avatar

Venus is a bit lower and Orion a bit higher in the eastern morning sky. Venus orbits closer to the Sun than Earth, and is racing ahead-of and away-from the Earth; the planet will vanish from view in mid-November as the Sun comes between it and the Earth. The waning crescent Moon appears thinner and closer to the horizon each morning in the eastern sky. Note: I used Stellarium’s new “Astronomical calculations” feature to generate the ephemeris for this image – I expect you’ll be seeing more of this. The Moon be in conjunction with the star Aldebaran on the Aug. 16th, appearing VERY close to each other, VERY early in the morning. Aldebaran is a orange giant star about 44 times the size of the Sun, located about 65 light years away. Aldebaran is positioned close to the ecliptic plane, and is frequently occulted by the Moon… just not this month. Jupiter is visible only for a short time … Continue reading

In the Sky This Week – August 1, 2017
avatar

Venus is still high in the eastern morning sky; the constellation Orion appears a bit higher each morning. The southern sky is filled with objects this week: the waxing gibbous Moon accompanies Jupiter and Saturn for several days. The Moon will appear very close to Saturn on the evening on August 2nd. The constellation Cetus appears in the predawn sky to the southeast. Cetus is depicted as a sea monster in Greek mythology, but is often referred to as “the whale” today. I know several astronomers who had a copy of H.A. Rey’s “The Stars: A New Way to See Them” when they were young – I still have my copy! I was overjoyed to see that Stellarium has a starlore set depicting constellations as drawn by H.A. Rey in his book. The constellation Cetus in Stellarium as drawn by H.A. Rey in his book “The Stars: A New Way to See Them.” The sky overhead – Aug 1, 2017 … Continue reading

What’s in the Sky July 25, 2017
avatar

Venus is still bright in the eastern predawn sky, but a little bit lower each morning. The constellation Orion is rising with the dawn; a little more of the constellation visible each morning. A wafer-thin waxing crescent Moon will be visible for a short time after sunset in the west on July 25th. Jupiter is visible low in the southwestern sky, and will be a little lower in the sky each evening after sunset. Saturn is high in the southern sky, and is a great target for telescope observers. Jupiter will be a scant 3° South of the Moon after sunset on July 28th. The Moon will be at First Quarter on the evening of July 30th, surrounded by Jupiter and Saturn, and the Southern Delta Aquariids Meteor Shower peaks on July 29-30th; this would be a great evening to host an astronomy outreach event! Apps used for this post: Stellarium: a free open source planetarium app for PC/MAC/Linux. NASA … Continue reading

What’s in the Sky July 18, 2017
avatar

Venus continues to dominate the morning sky in the east, but appears slightly lower in the sky each morning as it pulls ahead of us in its orbit. The waning crescent Moon will appear near Venus the the star Aldebaran on the mornings of July 19th and 20th. The New Moon will be on the 23rd. Jupiter and Saturn appear in the south-southwestern sky after sunset; Jupiter will appear slightly lower in the western sky each day as the Earth pulls ahead of Jupiter in its orbit. The constellations Pegasus and Andromeda appear low in the northeast sky after sunset; the wispy cloud of M31, the Andromeda galaxy, makes a good target for telescope observers. M31 is the nearest major galaxy to the Milky Way. It is 2.5 million light years distant, and heading straight at us; in a little over 4 billion years, it will collide with the Milky way, and the two galaxies will merge into a large … Continue reading

In the Sky This Week – July 11, 2017
avatar

Venus continues to be the “morning star” in the east, and will appear very close to the red giant star Aldebaran – the “eye of the bull” in the constellation Taurus. On the 11th, Venus will be 3◦ north of Aldebaran, over the course of the week, Venus’ day to day change in position relative to Aldebaran will be very noticeable. In the west, bright stars Vega and Altair are the last to fade in the oncoming dawn. On the 11th, a waning gibbous Moon will be rise in the east before midnight, and set in the west around 9:00 AM. On the 18th, a waning crescent Moon will rise shortly after 2:00 AM, and be visible until it is lost in the glare of the rising sun after 6:00 AM. The Moon will be at third quarter on the 16th, and will be visible from about 1:00 AM – 1:00 PM.* Jupiter and Saturn are visible in the southern sky … Continue reading

In the Sky This Week – July 4, 2017
avatar

Venus is the bright morning star in the eastern sky, attended by the Pleiades star cluster, and the bright star Capella to the northeast. The southern sky is adorned with several jewels this week: the Moon appears high in the southern sky before sunset as a waxing gibbous – a few days past first quarter. Jupiter and Saturn are both visible, as are the bright stars Antares and Spica. The full Moon will be on July 9th. The bright star Altair (featured in the classic SF film Forbidden Planet) rises in the east followed by the constellation Sagittarius to the southeast. Sagittarius is recognizable by “The Teapot” asterism low on the horizon. Sagittarius has several interesting deep sky objects to observe using telescopes; something cool you can do with the public during nighttime observing sessions is point to the Teapot’s spout and say “that’s where center of our Milky Way galaxy is!” Before dawn, the constellation Hercules sets in the west, and “The … Continue reading

In the Sky This Week – June 27, 2017
avatar

Venus remains high in the eastern morning sky, the Pleiades star cluster appears between Venus and the star Capella. The Moon is a waxing crescent, appearing in the west after sunset. Jupiter is high in the southwest, and Saturn is low in the southeast sky after sunset. There will be a conjunction of the Moon, Jupiter and the star Spica on the evenings of June 30th and July 1st. Here is the current positions of the planets in the solar system: Also in In the Sky This Week Weekly post on what you can see in the sky. In the Sky This Week – June 22, 2017 In the Sky This Week – June 27, 2017 In the Sky This Week – July 4, 2017 In the Sky This Week – July 11, 2017 What’s in the Sky July 18, 2017 What’s in the Sky July 25, 2017 In the Sky This Week – August 1, 2017 In the Sky This … Continue reading

It was Jupiter by the Moon this Morning
avatar

My wife called me this morning – her students were asking “what planet was by the Moon this morning?” There was frost on the ground (and cars), the air was very crisp, and apparently there was a lot of earthshine on the Moon. Jupiter was 1.4° south of the Moon in this morning’s sky. Even though the Moon was just a thin waning crescent, the students said it was very bright. Good on my wife’s students for witnessing this conjunction! … Continue reading

September Morning Sky, and October Conjunction
avatar

In the past couple weeks, I’ve been asked multiple times, as has my wife from her students: “What planet is that in the morning sky?” The one high and bright is Venus. Mars is below Venus, and a little to the north – right above the bright star Regulus. Jupiter is lower, near the horizon. On 17 Oct 2015, there will be a conjunction: Mars will be 24′ from Jupiter. That’s REALLY close, and I expect to see some spectacular images of the two posted later that day. Below is an illustration of the locations of the planets during the conjunction. They may look close together in the sky from your vantage point here on Earth, but they are anything but! … Continue reading