The July 2024 new moon occurs today as Earth reaches its farthest point from the sun, called aphelion.
The new moon will arrive on July 5 at 6:57 p.m. Eastern Time (22:57 UTC), according to the U.S. Naval Observatory, and two days later, the young moon will make a close pass of Mercury in the evening sky.
Earth reached aphelion today, meaning our distance from the Sun is greater than at any other time in its annual orbit. Earth’s orbit around the Sun is slightly elliptical, or oval, meaning our distance from our star can vary by as much as 3% throughout the year. This small variation is not significant enough to be noticeable to most observers.
New moons occur when the moon is directly between the sun and the earth. In many lunar calendar systems, they mark the beginning of the lunar month. Technically, the sun and moon are in conjunction, on the same north-south line that passes through the celestial pole. The lunar phase calendar is measured by the moon’s position relative to the earth, so a given phase occurs at the same time everywhere in the world. Any differences are due solely to the time zone you are in—in Melbourne, Australia, for example, the new moon occurs at 8:57 a.m. on July 6.
New moons are invisible unless there is an eclipse. Eclipses do not occur every new moon because the orbits of the Moon and Earth are not perfectly aligned; they are tilted relative to each other by about 5 degrees. The Moon’s shadow then “misses” Earth most of the time. (The next solar eclipse will not occur until October 2, 2024.)
Mercury’s Close Passage
On the evening of July 7, the Moon will pass next to Mercury as it exits new phase; the thin crescent will be somewhat 3 degrees north of Mercury at 2:33 p.m. Eastern Timeaccording to skywatching website In-the-Sky.org. At sunset, when the moon becomes visible, it will be about 16 degrees above the horizon; Mercury will be below the moon. But the planet won’t really be visible at all until about 9 p.m. (sunset that day is at around 8:29 p.m.. in New York; times are similar in cities like Chicago or Sacramento) and at that time it will only be 8 degrees high, so from anywhere in the mid-northern latitudes the conjunction will be a challenge to see – it will require a flat, clear, and bright horizon.
Observing the conjunction becomes easier as one approaches the equator. From lower latitudes (either north or south), the ecliptic, or the plane of Earth’s orbit projected into the sky, is at a steeper angle to the horizon. This means that the planets, all of which move within a few degrees of the ecliptic, tend to reach higher altitudes. (This is also why tropical sunsets seem so short, while those at higher latitudes to the north and south seem to drag on forever: in the tropics, the Sun approaches the horizon almost vertically, while in regions farther north or south, it approaches at a more gentle angle.)
From Miami, the conjunction will occur at 2:33 p.m. local time, but the Moon and Mercury will be higher in the sky; the sun sets at 8:16 p.m. It’s 1:30 PM local time and at this time the moon is 20 degrees high and Mercury is 18 degrees above the western horizon. Around 8:30 PM, Mercury should just become visible and it will still be about 12 degrees high, so with a clear horizon with no obstructions, we should be able to catch it.
From Bridgetown, Barbados (and similar latitudes), the Moon will appear to the right of Mercury and, at sunset, at 7:29 p.m. local timethe moon is 18 degrees high in the west, at 7 p.m. it is still 14 degrees above the horizon, as is Mercury, and both will be more visible than from the American continent
In the Western Hemisphere, the conjunction occurs in the afternoon, during daylight, but as one moves east, the timing of the conjunction shifts to the evening. From Madrid, Spain, the observing challenges are similar to those from New York (the two cities are at nearly the same latitude), but the conjunction occurs at 8:33 p.m. local time.
In the southern hemisphere, observation is a little easier: the days are shorter due to the austral winter. In Sao Paulo, the sun sets at 17:22 local time and, although the conjunction occurs at 15:33, still during the day, at sunset the moon will be 18 degrees high to the northwest and Mercury will appear above and to the left of the moon. Mercury will not be visible until about 18:00 and it will still be about 12 and a half degrees high. In Cape Town, where the conjunction occurs at 20:33 local time, sunset is at 5:51pm and the Moon and Mercury set at 7:34 p.m.; about a half-hour after sunset, the pair is about 13 degrees high in the northwest.
Visible planets
Venus will emerge into the evening sky, but it will still be largely lost in the solar glare; while it appears a little higher in the sky at sunset as one approaches the equator, it is no more than five or six degrees high when the sky begins to darken.
Saturn is the first planet to rise, at 11:40 p.m. on July 5 in New York City. In the constellation Aquarius, which is a fainter group of stars than many others, it will be quite distinct in its region of the sky. When the sky begins to clear around 4:30 or 5 a.m. (the morning of July 6), it will be about 41 degrees above the south-southeast horizon.
Mars will be visible in the early morning hours. As the year progresses, it will rise later and the planet will eventually fade into the light of the sun’s dawn. On the night of the new moon (July 5-6), in mid-northern latitudes, the planet will rise around 2 a.m. It rises at 2:03 a.m. in New York City, and the time will be similar in cities like Chicago (1:56 a.m. CDT), Denver (2:10 a.m. MDT), and Sacramento (2:18 a.m. PDT). Mars will be in the constellation Aries, which will be easy to spot because it is made up of fainter stars.
Jupiter rises after Mars, at 3:07 a.m. EDT in New York City. Jupiter is in Taurus, to the left and above Aldebaran, the brightest star in that constellation. Aldebaran is noticeably more orange and twinkles, making it easy to spot the planet, which is yellow-white and emits a steady glow.
This means that around 4:30 a.m. local time, in the mid-latitudes of the northern hemisphere, the three planets visible to the naked eye further from the Sun than Earth will form a sort of line in the sky, from the eastern horizon to the right, starting with Jupiter and ending with Saturn.
In the southern hemisphere, for example in Melbourne, Australia (where the new moon will occur on July 6), the three planets will also form a line, but this time up and to the left (because we are facing north). Saturn will also be higher in the sky. In Melbourne (and other locations in the southern mid-latitudes), Saturn will rise at 10:22pm Australian Eastern Standard Time on July 6; when the planet transits (crosses the north-south line in the sky) at 4:43am on July 7, it will be 58 degrees above the northern horizon. Mars will rise at 3:22am AEST and Jupiter at 4:47am. Jupiter’s position in the sky relative to Aldebaran will be reversed; Jupiter will appear below Aldebaran rather than above it (it will still appear to the left).
The stars of summer
For skywatchers in the northern hemisphere, around 10 p.m., the Summer Triangle is high in the eastern sky; the “top” star is Vega, the brightest star in Lyra, and it is near the zenith (about 70 degrees above the horizon). The other two stars in the Summer Triangle are Deneb and Altair, both to the east (left) of Vega; from a dark-sky site, the Milky Way can be seen inside the Triangle. The three stars form a rough right triangle with Altair at the southern end.
Turning left, heading north, we see the Big Dipper to the left (west) and slightly below Polaris, the North Star. Following the “pointers” (the two stars in front of the bowl of the Big Dipper, Dubhe and Merak) to Polaris and continuing straight, we encounter Cepheus, the king, and just below Cepheus is the “W” shape of Cassiopeia, which will be low to the northeast.
In the other direction, follow the handle of the Big Dipper and “bow to Arcturus”, the brightest star in Boötes, the shepherd, and continuing downwards you reach Spica, the brightest star in Virgo. Turning south (left) you see the bright red star Antares, the heart of Scorpius, and in the darker parts of the sky looking up (north) from Scorpius you see Ophiuchus the healer, with Sagittarius and its “teapot” shape to the left of Scorpius.
In the southern mid-latitudes, the winter stars can be seen, as darkness comes earlier. At 7 p.m., the sky is dark and the Southern Cross is well above the southern horizon, at about 65 degrees. To the left of the Cross (to the east) is Alpha Centauri, also called Rigil Kentaurus, our closest stellar neighbor. Farther east and closer to the horizon is Scorpius, although upside down (from a northern hemisphere observer’s perspective) and very high in the sky; Antares is at 47 degrees altitude at 7 p.m.
To the southwest, the keel of the ship, Puppis, is setting and is marked by Canopus, about 20 degrees above the southwest horizon. Canopus is the second brightest star in the night sky after Sirius. In the same region of the sky to the left (towards the south) are the Large Magellanic Cloud and the Small Magellanic Clouds, two satellite galaxies of the Milky Way.