As do all the other planets in the Solar System. But this illusion forms one of the most important markers on the sky, the line we call the ecliptic.<\/p>\n
The ecliptic is the invisible path that the Sun traces as it moves around the sky.<\/p>\n
Think of it like this: if the Sun were to drop breadcrumbs behind it like a cosmic Hansel and Gretel, this is the trail it would leave behind. The Sun can always be found on the ecliptic \u2013 it never deviates from it. But it also represents something else: the orbital plane of our planet.<\/p>\n
Read more:<\/strong><\/em><\/p>\n All of the planets in the Solar System occupy orbital planes similar to our own. This is because when the Solar System formed, billions of years ago, dust and gas surrounding our nascent star was pulled into a disc under the influence of gravity.<\/p>\n The planets we know today all formed within this disc and hence they all occupy planes similar to the ecliptic. In plain terms, when the planets are visible, they will always be near to this line (as in the image at the top of this page). For more on this, read our guide on how to find the planets in the night sky<\/a>.<\/p>\n It\u2019s this \u2018coplanar\u2019 nature of the Sun and planets that allows many of the events that captivate astronomers to occur so often. When our Moon and the Sun line up, we see an eclipse.<\/p>\n When a planet appears to be in the same region of sky as another, or our own Moon, we call it a conjunction<\/a>. Even seemingly rare events such as a transit of Venus<\/a>, are really quite frequent in cosmological terms.<\/p>\n If you look at a star chart, you may notice a second important line crossing the constellations, the celestial equator. This is simply a projection of Earth\u2019s terrestrial equator into space.<\/p>\n The celestial equator sits at an angle of 23.5\u00b0 to the ecliptic: a result of Earth\u2019s axial tilt. Using these two lines, we can make sense of the astronomical<\/span> points that mark the start of the seasons.<\/p>\n The points where the two lines meet mark<\/span> the equinoxes, when day and night are the same length. In the northern hemisphere, the equinox in mid-March heralds spring, the one in mid-September the beginning of autumn. At these two points in its orbit, Earth has no tilt relative to the Sun.<\/p>\n From the March equinox, the days slowly<\/span> lengthen until mid-June, when Earth reaches<\/span> the point in its orbit where it is at its greatest<\/span> tilt relative to the Sun \u2013 a solstice.<\/span><\/p>\n This is <\/span>both<\/span> the first day of summer and the longest<\/span> day of the year. At this point, the ecliptic and the<\/span> celestial equator are at their farthest apart.<\/p>\n There\u2019s another solstice six months later in mid-December, when the tilt of the poles<\/span> is completely reversed in relation to the Sun.<\/span> In the northern hemisphere, this marks the <\/span>start of winter and is also the shortest day.<\/p>\n The Sun always sits on the ecliptic, so it\u2019s easy to work out where the line is on any clear day. Looking at the whole year, we know that the Sun \u2013 and hence the ecliptic \u2013 is higher in the sky through the day in the summer months and lower during the winter.<\/span><\/p>\n But what about at night?<\/span> If you can work out where the ecliptic traces across the sky after darkness falls, you can work out where you might spot a planet.<\/p>\n The ecliptic sits low down in the morning, but in the evening it stretches high across the sky from east to west, making the dusk skies the best time to see Mercury and Venus, as they never stray far from the Sun.<\/p>\n In summer the ecliptic sits at a low<\/span> elevation by dusk, so any planets are mired in the atmospheric murk. The ecliptic\u2019s orientation swings from northwest-southeast in the evening to northeast-southwest in the morning.<\/p>\n In a reflection of the northern hemisphere spring, the ecliptic\u2019s evening path is now low down, but in the morning it stretches high across the sky from east to west. This makes the dawn skies the best time to see Mercury and Venus.<\/p>\n The ecliptic path in winter is quite high when it\u2019s dark, and moves higher until it reaches maximum elevation at midnight. This is a great time for observing planets, as you\u2019re able to look at them though less atmosphere.<\/p>\n \u00a0<\/p>\n Oppositions, another result of the Solar System being coplanar, occur when the Sun, Earth and another planet form a line, with Earth in the middle.<\/p>\n From our perspective, the planet is in the opposite position in the sky from our star. As such, only the superior planets \u2013 those with When a planet is at opposition it is usually at its closest to Earth and therefore appears larger than at any other time during its apparition. Due to its position relative to the Sun, a planet can be brighter than usual too.<\/p>\n![\""Our\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/08\/GettyImages-1148112202-1-53b2096.jpg?quality=90&resize=620%2C438"\" "\\"\"Our\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>What causes the seasons?<\/strong><\/h3>\n
![\""The\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/08\/GettyImages-140085796-1-3edf417-e1596546590541.jpg?quality=90&resize=620%2C410"\" "\\"\"The\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>How to find the ecliptic throughout the year<\/strong><\/h3>\n
Spring<\/h3>\n
Summer<\/h3>\n
![\""UK\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/05\/UK-summer-ecliptic-91416c3.jpg?quality=90&resize=620%2C410"\" "\\"\"UK\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Autumn<\/h3>\n
Winter<\/h3>\n
![\""UK\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/05\/UK-winter-ecliptic-0a4795f.jpg?quality=90&resize=620%2C414"\" "\\"\"UK\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Planet oppositions<\/h3>\n