One of the things that I like about astronomy is that there is always something new to look for. Yesterday, I wrote about Saturn being in conjunction. Today, I have a planetary grouping to talk about.
On Tuesday morning, if you get up a little before dawn and look to the southeast, you’ll be able to see three planets. Low to the horizon will be a very bright object. That is the planet Venus. About 25 degrees up and to the south a bit (that is a bit more than two hand widths) is the planet Jupiter. These will be easy to spot. But, if you look carefully at Venus, you will notice about a finger’s width away from it a much dimmer dot. That is the planet Mercury.
Over the past few days, Venus has been getting lower in the sky, and Mercury has been getting higher. They are actually at their closest as of a little while ago, but they will not be visible until just before dawn. Mercury is actually in front of Venus, from our perspective on Earth. Mercury is on our side of the Sun, and we are seeing Venus past the Sun on the far side of its orbit. Jupiter, too, is on the far side of the Sun from Earth.
This close approach by Mercury and Venus is called a conjunction. There is nothing really unusual or significant about a conjunction, it is merely an interesting thing to observe. This sort of thing happens all the time. The planets are not really close together at all, it is just from our vantage point that we see one behind the other.
But, if you keep looking towards the eastern sky at dawn, you’ll see an even more interesting grouping coming up on the morning of March 5, 2008. On that date, the Moon will be in the mix. There will be a very close grouping of Mercury, Venus, and the Moon.
In fact, it will be in conjunction with Mercury then at about 14:00 UT (that is about 8 am here in Fort Worth). In fact, the Moon will appear to pass directly in front of Mercury (and occultation) for people living in part of South America and western Africa. However, the Sun will already be up for them, so it will happen during daylight hours (and can be observed using a telescope). But, everyone with clear skies that morning will see Mercury and Venus in the eastern sky. If you have sharp eyes, and very good skies, you might also see the Moon. It will probably be difficult, because the Moon will be just a couple days before New Moon, so it will be only a tiny sliver of a crescent.
The Moon moves its own width in an hour of time. So, just about five hours later, it will be in conjunction with Venus. In fact, for people living in part of the Pacific and North America, the Moon will occult Venus, too. That, will be during the daytime here, but if it is clear it can be seen through the telescope. You can find details of these occultations, where they will be visible, and when, at the International Occultation Timing Association (IOTA) web site. For here in Fort Worth, the Moon will cover Venus just after 2:14 pm (14:14)Â CST, and it will reappear at about 3:25 pm (15:15)Â CST. However, the reappearance will be quite low in the sky, so we may or may not be able to see it.
Image created using Starry Night Pro 6