Viewing all 5 Visible Planets in one night

As the nights grow longer and the skies darker, we have the chance for the next few weeks to see all five planets visible to the naked eye in a single night. Of course, there are seven planets in our Solar System (not including Earth), but two (Uranus and Neptune) are just too faint to see without optical aid. However, the rest (Mercury, Venus, Mars, Jupiter and Saturn) are spread around the entire sky, adding a lot of brightness to our already-shiny Autumn and Winter skies. This article in the science blog EarthSky is an excellent guide to help you find each planet. Of course, to find Jupiter and Venus you need little guidance because they are so bright, but Mercury, Saturn and Mars will be easier to find with some assistance from a sky map.

And if you are ready to look deeper and see all 7 in one night, here is a chart to guide you to Uranus and Neptune. They are both just west of Jupiter, in the constellations Pisces and Aquarius.

Image courtesy NASA.

Planetary Lineup on May 21st

With all of the talk about May 21st, I felt it would be helpful to guide observers to a genuine, heavenly lineup that will create a beautiful pattern in the morning sky on the 21st and 22nd. During the entire month of May, the four nearest planets to Earth have been creating a beautiful sight in the morning sky just ahead of sunrise. On May 21st and 22nd, Mars, Mercury and Venus form a compact cluster. Bright Venus is the "guide star" to help you find this grouping in the east. You will want to look about 30-45 minutes before sunrise, and you will need binoculars to see Mercury and Mars, but Venus will shine brightly despite the glare of the soon-to-be-rising Sun. Jupiter is also quite visible in the sky, but each day pulls away to the upper right (toward the south-east) a bit more from the other three planets. Note that the image of the view toward the east, which comes courtesy of Sky & Telescope Magazine, demonstrates that astronomers are confident we'll have something to see the morning of the 22nd!

Venus, Jupiter, Mars and Mercury in Conjunction

Four of the five most-visible planets are bunched together in the morning sky, creating beautiful patterns along the eastern horizon at dawn for the next few weeks. Each day the four planets change slightly in position, with bright Venus guiding your eyes to the right spot on the horizon where you can see these four points of light. Use binoculars to find all four planets - Mercury and Mars are much fainter than Jupiter and Venus - and use this amazing animation on the Sky & Telescope website to find the exact pattern as it changes each day. In San Francisco, you will want to look for this between 5:00 and 5:30 am, before the glare of the sunrise washes out the view of the planets.

Five Weeks of Planets in Conjunction

We are entering a period of time in which several planets are going to be in close proximity to each other, creating special alignments called "conjunctions." Mars, Mercury, Jupiter and Venus are all occupying the same region of the sky from our Earth-bound point of view, and as these planets and our own planet are all in motion around the Sun, the pattern we see in the sky changes quite a bit from one night to the next. At this time, all of these planets are emerging from the glare of the brightening dawn sky, appearing in the east just minutes before sunrise. Therefore, the initial conjunction on April 19th is best visible with the aid of binoculars. But this is just the start of a five week period in which these planets move very close to one another, creating a beautiful series of patterns for the early morning observer.

Our planet moves nearly 2 million miles per day in its orbit around the Sun. The planets are also moving at high speed around the Sun in their respective orbits. Mercury and Venus move the fastest relative to Earth, and because of their unique position inside the orbit of Earth, we see their changing locations in the early morning just before sunrise, or in the evening just after sunset. The other planets, including Mars and Jupiter for the next few weeks, move more slowly from our point of view and move more steadily from east to west from one morning to the next. I'll be posting a regular series of updates over the next month as the various conjunctions come and go. The important thing for the observer is to find a good eastern horizon, dust off the binoculars, and be ready to get up just before sunrise to see these cosmic alignments.

Jupiter and Mercury: Prograde and Retrograde Motion

Elusive Mercury makes an appearance for the coming weeks in the evening sky, slowly progressing toward Jupiter as the two planets share the same space (from our point of view) just above the setting Sun. Although Jupiter is considerably farther away from Earth as Mercury, Jupiter's massive size more than makes up for that distance and makes it appear to us as a much brighter light on the horizon.

As Mercury rapidly arrives in the evening sky, it changes its location each evening quite a bit, and before long will be aligned with Jupiter, setting around the same time as Jupiter toward the end of March. As it reaches this point, it will then change its daily direction across the evening sky and move rapidly westward toward the Sun, something called "retrograde" motion. For a few weeks, people will say that "Mercury is in Retrograde" which is, from an astronomical point of view, very normal behavior for Mercury every few months. However, for many who follow astrology, this can be a very troubling time. Perhaps seeing Mercury with your own eyes changing location and moving gracefully across the sky, first in prograde motion (the basic motion of planets across the backdrop of stars, eastward), then in retrograde, will make its impact a little more friendly. Try it out for yourself and see.

A Must See: Four Planets and the Moon

This week the sky features four of the brightest planets in a beautiful lineup in the sunset sky. The illustration on the left, borrowed from Sky & Telescope Magazine, demonstrates how the planets all align themselves in a path across the sky known as the Ecliptic. This line in the sky, actually a gentle curve from west to east across the south part of the sky, is the plane of the Solar System as viewed from our observing platform on Earth. We see fast-moving Mercury close to the Sun, then Venus, Mars and Saturn, a most impressive line-up.

To set this into perspective, the young Moon emerges from the glare of the Sun on Tuesday 13th, moving somewhat parallel to the Ecliptic but each day a bit farther south of the Ecliptic. This is because the orbit of the Moon around the Earth is slightly inclined to the rest of the bodies in the Solar System. And as we just had a Total Solar Eclipse on Sunday, the Moon is following a path away from the Ecliptic into what is called the "descending node" south of the Ecliptic.

I will be talking about this at the California Academy of Sciences at their Nightlife event this Thursday in Golden Gate Park. If you are in or near San Francisco, please join me on the roof for Star Tours!

Seeing Mercury in the evening sky

Mercury makes its way into the evening sky, visible shortly after sunset for the next few weeks. The fleet-footed planet never strays far from the Sun from our point of view, so we get glimpses of Mercury in the evening, then the morning before sunrise, and again in the evening several times a year. Right now Mercury is going to be easy to find because it will move near Venus this week. Venus is the bright evening "star" in the west, shining through the glow of dusk, and Mercury, although dimmer, will be fairly easy to spot now that you know where to look.

Planetary Motion

The morning sky continues to be a busy place, showcasing just how much action is taking place in the Solar System. Saturn, a relatively slow moving outer planet is gradually rising up in the east, emerging each morning a minute or two earlier so that it will soon be a true morning star. As it graces the dawn sky just ahead of the sunrise, it is encountering the two fast-moving inner planets, Venus and Mercury. This week they have close encounters and beautiful alignments that will be a sight to see. The illustrations provide a sense of how far Venus and Mercury move over the course of just a few days. The passing of the waning Moon on the mornings of the 15th and 16th add a nice touch to an already impressive lineup of Solar System objects.

Morning Spectacle

Three planets make a nice showing in the early hours of the morning this week, with Mercury and Saturn having a close encounter. Autumn mornings are particularly interesting here in San Francisco because the weather is generally more reliable and the first light of dawn comes so late in the morning -- right now around 6:45 am with sunrise around 7:15 am. The view in the image shows what you can expect to see this week as Saturn and fast-changing Mercury line up on Thursday morning October 8th. All of this will stand in stark contrast to bright Venus, the brilliant beacon dominating the eastern sky in the morning.

Later this week there will be another amazing event in the morning sky. Stay tuned!